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. 2024 Mar 29;19(3):e0301354. doi: 10.1371/journal.pone.0301354

High-dose oral thiamine versus placebo for chronic fatigue in patients with primary biliary cholangitis: A crossover randomized clinical trial

Palle Bager 1,2,*, Lars Bossen 1, Rasmus Gantzel 1, Henning Grønbæk 1,2
Editor: Wan-Long Chuang3
PMCID: PMC10980237  PMID: 38551983

Abstract

Background & aims

Fatigue has high negative impact on many patients with primary biliary cholangitis (PBC) and treatment options are limited. Recently we showed favorable effects of four weeks of high-dose thiamine treatment on fatigue in patients with inflammatory bowel disease. We aimed to investigate the effect and safety of high-dose (600–1800 mg daily) oral thiamine treatment on chronic fatigue in patients with PBC.

Methods

Randomized, double-blinded, placebo-controlled crossover trial including patients with severe PBC-related fatigue. Participants were allocated 1:1 to either group 1) 4 weeks of high-dose thiamine, 4 weeks of washout, and 4 weeks of placebo; or group 2) 4 weeks of placebo, washout, and high-dose thiamine, respectively. Fatigue severity was quantified using the fatigue subscale of the PBC-40 questionnaire. The primary outcome was a fatigue reduction of ≥ 5 points after 4 weeks of high-dose thiamine treatment.

Results

We enrolled 36 patients; 34 completed the study. The overall mean reduction in fatigue was 5.0 points (95% CI: 2.5 to 7.5; p < 0.001) for the combined group 1 and group 2. Crossover analysis showed a mean increase in fatigue of 0.3 points (95% CI: -4.2 to 3.8) after high-dose thiamine treatment compared to a 1.4 points (95% CI: 6.2 to –3.4) mean reduction after placebo (p = 0.55). Only mild and transient adverse events were recorded.

Conclusion

Four weeks of high-dose oral thiamine treatment in patients with PBC was well tolerated and safe. However, high-dose thiamine was not superior to placebo in reducing PBC-related fatigue.

Trial registration

The trial was registered in the ClinicalTrials.gov (NCT04893993) and EudraCT (2020-004935-26).

Introduction

Primary biliary cholangitis (PBC) is a chronic, inflammatory immune-mediated liver disease ultimately leading to liver fibrosis, cirrhosis and end-stage liver disease [1–3]. PBC is a rare disease [4] with approximately 90% being women aged between 30 to 65 years at the time of diagnosis [3]. More than 50% of patients with PBC suffer from chronic fatigue, and 20% suffer from severe fatigue with a significant negative impact on their quality of life [5–7]. However, treatment options are limited [5, 8] with liver transplantation as the only documented treatment to reduce fatigue in patients with PBC [9].

PBC-related fatigue is usually measured on a subscale of the disease-specific PBC-40 questionnaire, which includes a fatigue domain of 11 questions. All answers are scored from 1–5, providing a total fatigue score between 11 and 55 [10]. In 2013, the mean total fatigue score was 20 in the general population, and a clinical cut-off for significant PBC-related fatigue was set at a score above 32 [11].

High-dose thiamine treatment reduces fatigue in patients with inflammatory bowel disease (IBD), Parkinson’s disease, and fibromyalgia [12–14]. We recently showed that high-dose oral thiamine was safe and effective in treating chronic fatigue in patients with IBD [15]. In that study, 55–75% of the patients had a significant decrease in their fatigue level and 45% of the patients reached a fatigue level similar to that of the general population. As the mechanism of action remains unknown, the favorable effects of thiamine may expand to a wider range of diseases and warrants investigations in patients with fatigue due to chronic liver disease and especially PBC where chronic fatigue is common and may be debilitating.

We hypothesized that high-dose thiamine reduces fatigue in patients with PBC and chronic fatigue. We aimed to investigate the efficacy and safety of four weeks of high-dose thiamine as a fatigue-reducing treatment in patients with PBC and severe chronic fatigue. Furthermore, we aimed to investigate the impact on quality of life measures following thiamine treatment.

Materials and methods

Study design

We conducted a randomized, double-blinded, placebo-controlled, crossover trial. Enrollment occurred between May 2021 and May 2022 at the Department of Hepatology and Gastroenterology at Aarhus University Hospital, Denmark. Patients were allocated 1:1 to group 1 (high-dose oral thiamine for 4 weeks in period 1, followed by 4 weeks of washout, followed by 4 weeks of oral placebo in period 2) or group 2 (oral placebo for 4 weeks in period 1, followed by 4 weeks of washout, followed by 4 weeks of high-dose oral thiamine in period 2). Individual variation in the responses was expected and minimized with the crossover design. To avoid the risk of a carryover effect, we added a 4-week washout period between period 1 and period 2. This duration was chosen as the high-dose thiamine half-life is < 5 hours and the thiamine storage time in the liver is less than 3 weeks [16, 17].

Participants

Patients with PBC for more than 3 months, age ≥ 18 years, a total fatigue score on the PBC-40 questionnaire > 32 and a fatigue duration > 6 months were eligible for study inclusion [10, 11]. The cut-off point for fatigue was equivalent to the clinical cut-off point for significant fatigue in the background population (mean + 2 standard deviations) [11]. We excluded pregnant women, patients with fatigue-causing co-morbidities (i.e. uncontrolled diabetes mellitus, dysregulated thyroid disease, anemia, and vitamin D deficiency), patients with impaired kidney function (glomerular filtration rate < 60 ml/min/1.73m2), patients who appeared to have low compliance, and patients who had planned surgery during the study period.

Randomization and masking

The randomization sequence with blocks of six consisting of three randomized to group 1 and three randomized to group 2 was performed by the Hospital Pharmacy at Aarhus University Hospital. They also labelled and packed the study medicine. All investigators and participants were blinded for the treatment.

Procedures

At the baseline visit, all included participants received tablets for the two treatment periods in two separate anonymized containers, labelled period 1 and period 2, each containing 200 tables. The thiamine tablet (SAD, Amgros I/S, Copenhagen) contained 300 mg thiamine hydrochloride. Placebo tablets were produced and delivered by Herlev Hospital Pharmacy, The Capital Region of Denmark. The daily dose depended on body weight (BW) and gender (female/male) according to the scheme: BW < 60 kg: 600/900 mg (2/3 tablets), BW 60–70 kg: 900/1200 mg (3/4 tablets), BW 71–80 kg: 1200/1500 mg (4/5 tablets), and BW > 80 kg: 1500/1800 mg (5/6 tablets). The dosing scheme was inspired by our recent trial in patients with IBD [15]. At the week 12 (end of trial) visit, the investigator counted the remaining tablets. Adherence was defined as >80% of the schemed study medication taken. The participants were reminded not to ingest any additional thiamine during the trial period and advised not to take the study drug in the evening to prevent temporary sleeplessness. At the week 12 visit the participants were asked to guess in which period they received thiamin tablets and placebo respectively.

Study visits in the clinic were scheduled at baseline and week 12 (end of trial), with the completion of questionnaires, drawing of blood samples, and safety assessments. At week 4 and week 8, the patients were given instructions electronically and completed the questionnaires directly in a REDCap database [18].

Fatigue was estimated using the fatigue sub-scale on the PBC-40 questionnaire [10] covering a domain of 11 questions where responses are given on a 5-point Likert scale, ranging from 1 ’not at all’ to 5 ’very much’. Consequently, the total fatigue score range is 11–55. The PBC-40 questionnaire is validated and translated into Danish.

The Danish version of the EQ-5D-5L was used to measure generic health-related quality of life (HRQoL). The EQ-5D-5L has been thoroughly validated (see also www.euroqol.org). The EQ-5D-5L classification system comprises five dimensions (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression), each with five levels. In addition, the EQ-5D-5L instrument yields a single overall health index score based on a visual analog scale (VAS) from 0–100 with high scores indicating high self-reported overall HRQoL [19].

Adverse events were registered and reported to the Ethics Committee in Central Denmark Region and the Danish Medical Agency.

Outcomes

The primary endpoint was a reduction of ≥ 5 points in the total fatigue score after 4 weeks of thiamine treatment compared to placebo. A reduction of ≥ 5 points was defined as clinically relevant since this would correspond to a ~10–15% reduction in the fatigue score among all included patients with possible fatigue scores between 33 and 55. The secondary endpoints covered the change in fatigue score at week twelve and changes in HRQoL at week 4, 8 and 12.

Statistical analysis

This 2 x 2 crossover study required 15 patients in each group to detect a mean difference between thiamine and placebo. This was based on the following assumptions: (i) a decrease of ≥ 5 points on the PBC-40 fatigue sub-scale, (ii) a standard deviation of 6.6 points based on published data for fatigue in the background population (11), (iii) an alpha value of 0.05, and a power of 80% [20]. This program was used for calculation: http://hedwig.mgh.harvard.edu/sample_size/size.html#cross.

We estimated approximately 10% drop-out demanding a total sample size of 36 patients.

Crossover analysis for fatigue scores averaged the between-treatment difference for each patient within each treatment period and then across both treatment periods, providing an estimate of treatment effect [21, 22]. The estimated treatment difference, 95% confidence interval (CI) and p-values were adjusted for period and sequence effects in the variance model analysis. To check for a potential carryover effect, we analyzed the within-subject sums of the results from both periods and compared the two groups, using an unpaired t-test. Subsequently, we did a parallel group comparison considering group 2 as subject to delayed thiamine treatment (period 2). In our primary analytical approach per the crossover analysis, group 1 was considered to be in the thiamine treatment group at week 4 and in the control group at week 12, whereas group 2 was considered to be in the control group at week 4 and in the thiamine treatment group at week 12. Differences in fatigue between week 4 and week 12 were compared between groups, using an unpaired t-test. Sensitivity analysis excluding non-adherent participants was performed. We aimed to do both intention-to-treat (ITT) analysis and per-protocol analysis.

Study data were managed using the REDCap data capture tool hosted at Aarhus University [18]. Data analysis was conducted in Stata.

The trial was approved by the Ethics Committee in Central Denmark Region (j.no. 76946) and the Danish Medical Agency (EudraCT j.no. 2020-004935-26). The trial was conducted in accordance with the Declaration of Helsinki and the GCP principles and was monitored by the GCP unit at Aarhus and Aalborg University Hospitals. The trial was registered in the ClinicalTrials.gov (NCT04893993).

Results

Thirty-six of 74 patients with PBC and chronic fatigue were assessed for eligibility, enrolled and randomly assigned to the treatment sequences (Fig 1). In brief, the fourteen patients who were excluded due to fatigue-causing comorbidity included: fibromyalgia, dysregulated diabetes, cancer, apoplexia, anemia, Sjögren’s Syndrome, vitamin D deficiency, and combinations hereof.

Fig 1. Consolidated standards of reporting trials diagram.

Fig 1

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The baseline characteristics are shown in Table 1. The median fatigue score was 39 in group 1 and 40 in group 2.

Table 1. Baseline characteristics.

Group 1: Group 2:
thiamine followed by placebo (n = 18) placebo followed by thiamine (n = 18)
Demographics
Age, years, mean (SD) 56 (10) 61 (9)
Sex, female, n (%) 16 (89) 17 (94)
Body Mass Index, mean (SD) 29 (7) 27 (6)
Disease, n (%)
AIH overlap 2 (12) 2 (12)
Liver cirrhosis 1 (6) 1 (6)
Biochemistry, median (IQR)
ALAT (U/l) 40 (29–65) 32 (27–45)
Bilirubin (μmol/l) 11 (8–13) 8 (6–10)
Alkaline phosphatase (U/l) 134 (94–155) 128 (101–175)
FIB-4 score (U/l) 1.2 (1.0–1.5) 1.2 (0.9–1.8)
CRP (mg/l) 4 (1–8) 4 (1–9)
sCD163 (mg/l) 3.2 (2.8–4.0) 3.4 (3.0–3.7)
WBC (109/l) 6 (2) 7 (2)
Haemoglobin (g/dl) 13.7 (12.7–14.0) 14.0 (13.4–15.4)
Platelet count (109/l) 253 (218–293) 273 (235–284)
Comorbidity, n (%)
Osteoporosis 4 (24) 6 (35)
Diabetes 2 (12) 2 (12)
Hypertension 3 (18) 2 (12)
Medication, n (%)
UDCA 18 (100) 18 (100)
Bezafibrate 6 (35) 0 (0)
Obethicolic acid 0 (0) 0 (0)
Fatigue and HRQoL, median (IQR)
PBC-40, fatigue sub-scale 39 (37–42) 40 (37–41)
EQ-5D-5L VAS 65 (50–75) 75 (66–80)
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Abbreviations: AIH, autoimmune hepatitis; CRP, C-reactive protein; WBC, white blood cells; UDCA, ursodeoxycholic acid; EQ.5D-5L, European Quality of life scale; SD, standard deviation; IQR, interquartile range.

Two participants dropped out during period 1; one from group 1 due to SARS-CoV-2 infection and one from group 2 who withdrew informed consent. None of the drop-outs were related to study medication. In the following analysis, we used data from the 34 patients who completed the study. Due to missing data from the drop-outs, we performed per-protocol analysis and abstained from doing ITT analysis.

The overall mean reduction of fatigue in the PBC-40 fatigue subscale score was 5.0 points (95% CI 2.5 to 7.5; p < 0.001) for the combined group 1 and group 2. Both groups increased by 2 points in fatigue score during the washout period. Given this and a confirmatory analysis showing a non-significant inter-group difference in the sum of fatigue at week 4 and week 12, we assumed no carryover effect. Therefore, we assessed the delayed treatment model. The crossover analysis showed a mean increase in fatigue of 0.3 points (95% CI: -4.2 to 3.8) after high-dose thiamine treatment compared to a 1.4 points (95% CI: 6.2 to –3.4) mean reduction after placebo (p = 0.55).

Furthermore, no statistical difference in HRQoL measures were detected in the crossover analysis (p = 0.90) (Table 2).

Table 2. Crossover analysis of fatigue and health-related quality of life.

Group 1: Group 2:
thiamine followed by placebo placebo followed by thiamine
(n = 17) (n = 17)
Week 4 Week 12 Difference Week 4 Week 12 Difference p–value
Fatigue
PBC40 34.6 (7.1) 33.2 (7.5) -1.4 (2.3) 35.5 (7.2) 35.8 (5.3) 0.3 (1.9) 0.55
• fatigue subscale
HRQoL
EQ5D VAS 68.3 (13.0) 69.5 (18.7) 1.2 (5.0) 69.1 (15.4) 70.2 (13.2) 1.1 (4.1) 0.90
• range 0–100
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Note: Data are mean, (SD).

Abbreviations: EQ5D VAS, European Quality of life, VAS.

Forty-seven percent (n = 8) in group 1 and 29% (n = 5) in group 2 experienced an improvement ≥ 5 points while on thiamine treatment compared with 41% (n = 7) and 24% (n = 4) while on placebo, respectively (p = 0.71).

Fig 2 illustrates the course of fatigue scores during the study period for both groups.

Fig 2. Fatigue scores between groups.

Fig 2

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At baseline six patients received Bezafibrate in Group 1 compared to none in Group 2. Supplementary analysis stratifying for Bezafibrate did not substantially change the main results. One patient in each group was < 80% adherent to the treatment when receiving thiamine. Sensitivity analysis excluding the two non-adherent participants showed an overall mean reduction of fatigue in the PBC-40 fatigue subscale score of 5.4 points (95% CI 2.8 to 7.2; p < 0.001) for the combined group 1 and group 2. In addition, crossover analysis showed a mean reduction in fatigue of 0.1 points (95% CI: -4.2 to 4.4) after high-dose thiamine treatment compared to a 1.8 points (95% CI: -3.8 to 6.8) mean reduction after placebo (p = 0.60).

Additional analysis found no correlations between the participants’ characteristics and reduction in fatigue in the study period. This also includes the individual baseline cognitive symptoms sub-score on the PBC-40. Upon unblinding, it was revealed that 20 participants (58%) correctly surmised the treatment allocation.

Adverse events (AEs) and serious adverse events (SAEs) were monitored continuously during the study. No SAEs related to the study drug were detected. Three SAEs occurred and required brief hospital admissions, including SARS-CoV-2 infection (placebo-period), other infection (thiamine-period), and exacerbation of chronic obstructive pulmonary disease (washout-period). None of the SAEs were judged as related to the study drug. A few temporary AEs were recorded including sore throat/cold symptoms (3 in the thiamine-period and 2 in the placebo-period), elevated ALAT (1 in the placebo-period), fall on a pavement (1 in the placebo-period), and angina pectoris event (1 in the thiamine-period).

Discussion

There is an unmet need for new and better treatments of fatigue in PBC patients. To our knowledge, this is the first trial to investigate the safety and efficacy of high-dose oral thiamine on chronic fatigue in patients with PBC. In this study four weeks of high-dose oral thiamine was well tolerated and safe in patients with PBC. However, we could not demonstrate any significant effect of high-dose thiamine on chronic fatigue compared to placebo. These results diverge from the recent study in patients with IBD where four weeks of high-dose oral thiamine was superior to placebo in reducing chronic fatigue [15].

The mechanisms behind the effect of thiamine on fatigue are still unsettled [23–25]. Thus, etiology of chronic fatigue in patients with PBC may differ from that of chronic fatigue in patients with IBD. We observed no differences in the effect when stratifying for self-reported cognitive symptoms, as suggested to be a factor for fatigue in patients with PBC [26]. Neither did we reveal any predictors for effect from high-dose thiamine.

Fatigue remains a burdensome companion for many patients with PBC and interventions that can reduce fatigue are highly needed [27]. This could be of any origin. Small scale studies on pharmaceutical products like seladelpar [28] and S-adenosyl-L-methionine [29] have been performed and showed effect on HRQoL, including fatigue. However, larger studies are needed [27]. According to the clinicaltrials.gov database, two non-pharmacological interventions have been identified. A mindfulness study planned in the US is terminated, while a home exercise study has been completed in the UK [30] but not yet reported. In addition to intervention studies, there is a need for research that can contribute to a better understanding of the pathogenesis and mechanisms of fatigue in PBC (and more broadly). Given that fatigue is a non-specific symptom observed in a broad range of diseases, exploring fatigue-alleviating solutions from other diseases in a PBC population could be valuable [31]. Specifically, interventions tested in other autoimmune diseases are worth investigating. The present study demonstrates how findings from IBD were applied within a PBC population.

Despite the strong design of this study, it has some limitations. Firstly, even though we did a straight forward power calculation a priory accounting for drop-outs the study might be underpowered. A larger study may show effect of high-dose thiamine. However, a pragmatic implication of our finding could be to consider refraining from any further studies on PBC-related fatigue and high-dose thiamine. Furthermore, it is known that the smell and taste of vitamins can be intense, potentially posing a challenge to the blinding of the study. However, only 58% of the participants surmised the correct treatment allocation, which indicates a reliable blinding of the study drug.

In conclusion, this clinical study showed that four weeks of high-dose oral thiamine treatment was similar to placebo in reducing fatigue in patients with PBC and chronic fatigue. The thiamine treatment was safe and well tolerated by the patients. Further studies are needed to help the group of patients with PBC suffering from chronic fatigue.

Supporting information

S1 Checklist. CONSORT 2010 checklist of information to include when reporting a randomised trial*.

(PDF)

pone.0301354.s001.pdf (49.4KB, pdf)
S1 Data

(XLSX)

pone.0301354.s002.xlsx (21.2KB, xlsx)
S1 File

(PDF)

pone.0301354.s003.pdf (100.7KB, pdf)

Acknowledgments

We thank the GCP unit at Aarhus and Aalborg University Hospital, Denmark, for advice and rigorous monitoring. The study was partly funded by donations from Helsefonden.

Data Availability

All relevant data are within the manuscript and its Supporting Information files.

Funding Statement

Helsefonden The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Decision Letter 0

Wan-Long Chuang

2 Jan 2024

PONE-D-23-41263Please find enclosed a manuscript for PLOS ONE entitled: 

High-dose oral thiamine versus placebo for chronic fatigue in patients with primary biliary cholangitis: A crossover randomized clinical trialPLOS ONE

Dear Dr. Bager,

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PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: No

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This randomized, double-blinded, and placebo-control study investigated the effect of thiamin in treating fatigue in PBC patients. Four-week thiamin treatment was administered before or after placebo. PBC-40 was used to assess the changes of fatigue. The study concluded that thiamin administration did not improve fatigue when compared with placebo. Overall, this study was well-written and scientifically sound.

Comments

1. The limitation of study is the patient number. Owing to lack of reference study, larger number of patients would be helpful to validate the treatment efficacy.

2. In group 1, more patients took Bezafibrate that had beneficial effect in fatigue symptom. It would compromise the analysis, although there was negative result of thiamin treatment.

3. Many conditions may also contribute to fatigue. No further description was noted.

4. How to explain the improvement of PBC-40 score in placebo and similar patterns of score changes during entire study period of both groups? true double-blinded?

Reviewer #2: General comments:

This manuscript presents the results of a crossover trial of oral thiamine treatment on chronic fatigue in participants with primary biliary cholangitis. The manuscript is well-written and easy to follow. As far as I can tell, all necessary sections and components are in place.

Given this is a small trial, the small sample size limits the statistical methods choices. Thus, I found this manuscript straightforward, and don't feel I have much to offer to improve this manuscript. In my specific comments below I have a few suggestions on changes that could be made.

Specific comments:

1. The most limiting factor, at least when trying to assess efficacy, is the sample size. I found the sample size acceptable but on the low end for a phase 1 safety trial, but very much lacking to estimate efficacy with any robustness. Thus, I'm not sure how to feel about the efficacy results. Is the aim of the efficacy results proof of concept? I fully understand the safety results based on the justification in the introduction, but the efficacy results feel as though they were doomed from the start and I'm not sure whether the efficacy analyses meet criterion #3 (https://journals.plos.org/plosone/s/criteria-for-publication).

2. (lines 148-152) I suggest including a citation or some information on the formula or program that was used to calculate the sample size estimate.

3. (line 149) You may also want to explain a little bit about the choice of at least of 5 point decrease on the fatigue subscale. I operationalized that as dropping a point on 5 of the 11 questions. That seems reasonable to me, though it's not a scale I know well.

4. (Table 1) I suggest including standardized mean differences (but not p-values) to assess the differences between the groups.

Reviewer #3: Bager et al. conducted a crossover randomized clinical trial to investigate the effect and safety of high dose oral thiamine treatment on chronic fatigue in patients with PBC. They found that high dose thiamine treatment was safe but was not superior to placebo in reducing PBC-related fatigue.

Major comments

1. The primary outcome described in the abstract and the methods section are not exactly the same. Please clarify.

2. What is the primary analysis of this study (intention-to-treat analysis or per-protocol analysis or both)? Please clarify. It is suggested to present the results of both intention-to-treat and per-protocol analysis in the main text or in the supplementary file.

3. How to determine the case numbers in each group before the trial?

4. How to diagnose the primary biliary cholangitis? What’s the criteria? The proportion of liver cirrhosis in these study is very low, what’s the reason? Does the low ratio of cirrhosis implicate selection bias?

5. What’s the dose of URSO and what kind of patients received the bezafibrate? The reasons of fourteen patients with fatigue-causing comorbidity should be disclosed.

6. In the results section, the authors stated that sensitivity analysis excluding the two non-adherent participants did not change the results. However, there is no relevant statement describing the process of sensitivity test in the methods section. Please add it. In addition, please also present the data of sensitivity test in the main text or in the supplementary file.

7. In the results section, the authors mentioned three SAEs occurred and a few temporary AEs were recorded. Please list in a table how many patients in each group experienced each AE and SAE.

8. In Figure 1, two patients were excluded in the screening process due to low compliance. However, “low compliance” is not an exclusion criterion in the methods section. Please clarify.

9. In Figure 1, three patients were excluded in the screening process due to other reasons. Please elaborate on the reasons.

Minor comments

1. Table 2: in the column of Group 1, the difference of EQ5D VAS between Week 12 and Week 4 is presented as “2.2”. Should the data be corrected to “1.2” (69.5-68.3=1.2)? Please clarify.

2. Figure 1: a spelling error is noted. Should “impaired kidney funktion” be corrected to “impaired kidney function”? Please clarify.

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

**********

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PLoS One. 2024 Mar 29;19(3):e0301354. doi: 10.1371/journal.pone.0301354.r002

Author response to Decision Letter 0

31 Jan 2024

Authors response to the reviewers

Reviewer #1:

Comment 1:

The limitation of study is the patient number. Owing to lack of reference study, larger number of patients would be helpful to validate the treatment efficacy.

Response:

We partly agree that number of patients included may be a limitation. However, the number of patients were estimated based on a specific power calculation based on our data from IBD patients. A larger study population may have revealed some effect. However, our results were not close to show a statistically significant difference. Based on the obtained results a power calculation for larger study would have demanded approximately 140 patients. Assumptions: 1) a decrease of ≥ 5 points on the PBC-40 fatigue sub-scale, 2) a within patient standard deviation of 12 points, 3) an alpha value of 0.05, and a power of 90% 4) approximately 10-15 % drop-outs. However, as we write in the discussion, the study might have been underpowered; but we also suggest that thiamine as a treatment option for PBC-fatigue could be rejected as a result of our findings.

Comment 2:

In group 1, more patients took Bezafibrate that had beneficial effect in fatigue symptom. It would compromise the analysis, although there was negative result of thiamin treatment.

Response:

Thank you for this observation. However, supplementary analysis stratifying for Bezafribrate showed similar results. We have added a sentence regarding this in the Results section (page 12, lines 205-7).

Comment 3:

Many conditions may also contribute to fatigue. No further description was noted.

Response:

We agree and since fatigue can be multifactorial, we excluded patients who had obvious other reasons for fatigue than PBC and the most frequent reasons are now mentioned in the method section. In addition, the RCT design aim to equally distribute participants who might have other reasons for fatigue.

Comment 4:

How to explain the improvement of PBC-40 score in placebo and similar patterns of score changes during entire study period of both groups? true double-blinded?

Response:

Thank you for this relevant comment. The most obvious explanation is that the effect of thiamine was not superior to placebo. It is no surprise that both groups had a decrease in fatigue-scores in the first period, as the participants was hoping for an effect. In the first period, none of the participants had tried any of the blinded treatments before. Based on individual experiences in period one, some participants would probably be able to guess the random allocation when exposed for the study drug in period two. This could be due to taste, smell of urine or due to the effect on fatigue. However, as mentioned in the discussion, only 58% guessed their allocation sequence correctly indicating a successful blinding.

Reviewer #2:

Comment 1:

The most limiting factor, at least when trying to assess efficacy, is the sample size. I found the sample size acceptable but on the low end for a phase 1 safety trial, but very much lacking to estimate efficacy with any robustness. Thus, I'm not sure how to feel about the efficacy results. Is the aim of the efficacy results proof of concept? I fully understand the safety results based on the justification in the introduction, but the efficacy results feel as though they were doomed from the start and I'm not sure whether the efficacy analyses meet criterion #3 (https://journals.plos.org/plosone/s/criteria-for-publication).

Response:

Please see our response to reviewer 1 (Q1) above.

In addition, we agree that we may have been too optimistic regarding the ‘expected’ efficacy of thiamine vs placebo (i.e. we expected ≥5 points improvement from thiamine compared to placebo). On the other hand, a 5-point reduction is between 10-15% of the baseline fatigue score and less would – in our opinion – not be clinically relevant. Further, our optimism was based on the convincing results from the Inflammatory Bowel Disease-Fatigue-Thiamine study. Moreover, as stated in Q1, our results did not suggest a difference between thiamine and placebo, hence the missing efficacy was most likely just because thiamine does not improve fatigue in PBC patients.

Comment 2:

(lines 148-152) I suggest including a citation or some information on the formula or program that was used to calculate the sample size estimate.

Response:

We used this web-service for calculations: http://hedwig.mgh.harvard.edu/sample_size/size.html#cross

This has also been added to the manuscript (page 9, line 155).

Comment 3:

(line 149) You may also want to explain a little bit about the choice of at least of 5 point decrease on the fatigue subscale. I operationalized that as dropping a point on 5 of the 11 questions. That seems reasonable to me, though it's not a scale I know well.

Response:

Thanks for pointing this out. We have added a sentence about this under ‘outcomes’ in the methods section and provide a deeper explanation here: We do not know of any similar previous studies, and thus we had to choose our own clinically relevant outcome. We chose a 5-point reduction for two reasons: 1) The possible scores on the fatigue subscale ranges between 33-55, as the minimum score for significant fatigue is 33. Thus a 5-point reduction equals a ~10-15% reduction in the fatigue score which we argue is clinically relevant; 2) Based on data collected in other clinical PBC studies at our site (data not published), we expected the median fatigue score to be around 38 among the included patients. Thus, a 5-point reduction would bring almost 50% of the patients into the spectrum of ‘normal fatigue’.

Comment 4:

(Table 1) I suggest including standardized mean differences (but not p-values) to assess the differences between the groups.

Response:

Most data in Table 1 are reported as median (IQR). The reason for this is that some of the biochemistry data doesn't have a normal distribution. We can change the presentation of data in Table and add differences (+/- p-values). However, we believe that the current presentation of data will give the best overview.

Reviewer #3:

Comment 1:

The primary outcome described in the abstract and the methods section are not exactly the same. Please clarify.

Response:

Good observation. The wording in 'outcomes' in the 'M+M' section has been changed.

Comment 2:

What is the primary analysis of this study (intention-to-treat analysis or per-protocol analysis or both)? Please clarify. It is suggested to present the results of both intention-to-treat and per-protocol analysis in the main text or in the supplementary file.

Response:

Good point. Due to missing data, we only performed per-protocol analysis. We have added text to both the 'Statistics' and the 'Results' sections.

Comment 3:

How to determine the case numbers in each group before the trial?

Response:

Please see our response to reviewer 2 (Q1) above.

Comment 4:

How to diagnose the primary biliary cholangitis? What’s the criteria? The proportion of liver cirrhosis in this study is very low, what’s the reason? Does the low ratio of cirrhosis implicate selection bias?

Response:

Thank you for this relevant comment. Primary biliary cholangitis was diagnosed in accordance with international consensus diagnostic criteria (reference #5 'EASL Clinical Practice Guidelines: The diagnosis and management of patients with primary biliary cholangitis. J Hepatol. 2017'). In the present study, 2 patients (6%) had cirrhosis, which is slightly lower than in a recent Danish study reporting a cirrhosis prevalence of 13% among patients with PBC. This may be due to our exclusion criteria including impaired kidney function and anaemia – two common complications among patients with cirrhosis.

Comment 5:

What’s the dose of URSO and what kind of patients received the bezafibrate? The reasons of fourteen patients with fatigue-causing comorbidity should be disclosed.

Response:

A) In Denmark, standard dose of UDCA was 750mg/day up until the introduction of bezafibrate (around 2019 in Denmark, and thus before the start of inclusion into this study). Since then, we have continued on 750mg/day if patients were sufficiently treated, i.e. their ALP was below 1.5XULN (160 I/U). If not, they were increased to 10-15mg/kg/day, and if that did not bring ALP below 160 I/U we have initiated treatment with bezafibrate. Another indication for bezafibrate treatment was progression on either liver stiffness (transient elastography) or liver fibrosis (biopsy). The last indication is based on an individual clinical judgement from hepatologists.

B) In brief, the fourteen patients who were excluded due to fatigue-causing comorbidity included: fibromyalgia, dysregulated diabetes, cancer, apoplexy, anemia, Sjögren's Syndrome, vitamin D deficiency, and combinations hereof. This sentence has also been added to the manuscript (page 10, line 180-2).

Comment 6:

In the results section, the authors stated that sensitivity analysis excluding the two non-adherent participants did not change the results. However, there is no relevant statement describing the process of sensitivity test in the methods section. Please add it. In addition, please also present the data of sensitivity test in the main text or in the supplementary file.

Response:

The analysis excluding the 'non-adherent' patients have now been described both in the method- and the results section.

Comment 7:

In the results section, the authors mentioned three SAEs occurred and a few temporary AEs were recorded. Please list in a table how many patients in each group experienced each AE and SAE.

Response:

Events are now followed by description of treatment-group in brackets in the text.

Comment 8:

In Figure 1, two patients were excluded in the screening process due to low compliance. However, “low compliance” is not an exclusion criterion in the methods section. Please clarify.

Response:

Good point. This exclusion criterion has been added to the manuscript text.

9. In Figure 1, three patients were excluded in the screening process due to other reasons. Please elaborate on the reasons.

Response:

Sure. Two cases had fatigue for other reasons (than comorbidity) and one was newly diagnosed with PBC.

Minor comment 1:

Table 2: in the column of Group 1, the difference of EQ5D VAS between Week 12 and Week 4 is presented as “2.2”. Should the data be corrected to “1.2” (69.5-68.3=1.2)? Please clarify.

Response:

Thank you for identifying this typing error. The correct number is 1.2 and has been changed in Table 2.R1

Minor comment 2:

Figure 1: a spelling error is noted. Should “impaired kidney funktion” be corrected to “impaired kidney function”? Please clarify.

Response:

Thank you. The spelling has been corrected.

Decision Letter 1

Wan-Long Chuang

18 Feb 2024

PONE-D-23-41263R1High-dose oral thiamine versus placebo for chronic fatigue in patients with primary biliary cholangitis: A crossover randomized clinical trialPLOS ONE

Dear Dr. Bager,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Apr 03 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

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  • A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

  • An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Wan-Long Chuang, M.D., Ph.D.

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

Reviewer #3: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: No

Reviewer #2: (No Response)

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: (No Response)

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: (No Response)

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: (No Response)

Reviewer #3: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This manuscript may report as a preliminary results of clinical trial rather than a complete study. It needs more patients enrolled for consolidate findings.

Reviewer #2: (No Response)

Reviewer #3: Although the authors had replied the questions raised by the reviewers, there are still some points that needed to be clarified or revised.

1. The intervention of this study is supplementation of high dose thiamine for four weeks. The authors have explained the half life and storage time of thiamine; however, this evidence only can explain the duration designed for the wash-out period. How the authors make sure that the duration of supplementation (four weeks) is long enough to be therapeutic effective in these patients. If it is possible that the negative finding resulted from the short duration of supplementation. In addition, the authors did not present the serum level of thiamine of the patients before and after thiamine supplementation. It is necessary to show the serum data of thiamine to prove the dose and duration of supplementation is effective.

2. The primary outcome of this study is a reduction of total fatigue score. As mentioned by the previous reviewers, many clinical disorders and conditions can affect the status of fatigue. The authors also have excluded patients with other comorbidities that would lead to chronic fatigue, however, many other comorbidities should also have to be excluded, such as moderate to severe degree of acute or chronic cardiac and pulmonary diseases, adrenal insufficiency, sarcopenia, obesity, malnutrition, and so on. The authors have to clarify the surveillance and exclusion criteria involved fatigue-related comorbidities.

3. Patients' nutrition status (malnutrition, obesity, sarcopenia, etc.) and daily intake amount would have big impacts on fatigue score. The authors have to present the information about daily intake of calories and protein, the nutrition status of patients before and after thiamine supplementation as well.

4. In patients with PBC, liver function has a great influence on the clinical fatigue of them. The authors also have to present the liver function of patients before and after thiamine supplementation.

5. There are some spelling mistakes that need to be corrected, such as the 3 impaired kidney fun"k"tion in figure 1.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PLoS One. 2024 Mar 29;19(3):e0301354. doi: 10.1371/journal.pone.0301354.r004

Author response to Decision Letter 1

22 Feb 2024

Authors response to the reviewers

Reviewer #1:

This manuscript may report as a preliminary results of clinical trial rather than a complete study. It needs more patients enrolled for consolidate findings.

Response:

It may be true that more patients could have shown other results. However, we made a straight forward power calculation prior to study start. In addition, we would refer to our previous response to reviewer #1:

'We partly agree that number of patients included may be a limitation. However, the number of patients were estimated based on a specific power calculation based on our data from IBD patients. A larger study population may have revealed some effect. However, our results were not close to show a statistically significant difference. Based on the obtained results a power calculation for larger study would have demanded approximately 140 patients. Assumptions: 1) a decrease of ≥ 5 points on the PBC-40 fatigue sub-scale, 2) a within patient standard deviation of 12 points, 3) an alpha value of 0.05, and a power of 90% 4) approximately 10-15 % drop-outs. However, as we write in the discussion, the study might have been underpowered; but we also suggest that thiamine as a treatment option for PBC-fatigue could be rejected as a result of our findings.'

Reviewer #2:

No comments from reviewer #2.

Reviewer #3:

Although the authors had replied the questions raised by the reviewers, there are still some points that needed to be clarified or revised.

Comment 1:

The intervention of this study is supplementation of high dose thiamine for four weeks. The authors have explained the half life and storage time of thiamine; however, this evidence only can explain the duration designed for the wash-out period. How the authors make sure that the duration of supplementation (four weeks) is long enough to be therapeutic effective in these patients. If it is possible that the negative finding resulted from the short duration of supplementation. In addition, the authors did not present the serum level of thiamine of the patients before and after thiamine supplementation. It is necessary to show the serum data of thiamine to prove the dose and duration of supplementation is effective.

Response:

i) Duration of treatment can be discussed. However, in other studies the effect on fatigue was obtained after 3-4 weeks. Based on these studies a thiamine exposure of 4 weeks was chosen.

1) Bager P, Hvas CL, Rud CL, Dahlerup JF. Randomised clinical trial: high-dose oral thiamine versus placebo for chronic fatigue in patients with quiescent inflammatory bowel disease. Aliment Pharmacol Ther. 2021;53:79-86. [28 days]

2) Costantini A, Pala MI. Thiamine and fatigue in inflammatory bowel diseases: an open-label pilot study. J Altern Complement Med. 2013;19:704-8. [20 days]

ii) In this study we did not collect data on serum-thiamine.

Firstly, because the possibility for levels below the normal range is low in a Danish population. In our IBD-study we found a few patients with levels below the normal range. However, the thiamine-effect was found not to be depended of the serum-levels.

1) Bager P, Hvas CL, Rud CL, Dahlerup JF. Randomised clinical trial: high-dose oral thiamine versus placebo for chronic fatigue in patients with quiescent inflammatory bowel disease. Aliment Pharmacol Ther. 2021;53:79-86).

2) Bager P, Hvas CL, Hansen MM, Ueland P, Dahlerup JF. B-vitamins, related vitamers, and metabolites in patients with quiescent inflammatory bowel disease and chronic fatigue treated with high dose oral thiamine. Mol Med. 2023;29:143.

Secondly, the dose given in this PBC-study is up to 100 fold the recommended daily dose of thiamine. Consequently, a low level of serum-thiamine at baseline will be insignificant compared to the high-dose exposure.

Comment 2:

The primary outcome of this study is a reduction of total fatigue score. As mentioned by the previous reviewers, many clinical disorders and conditions can affect the status of fatigue. The authors also have excluded patients with other comorbidities that would lead to chronic fatigue, however, many other comorbidities should also have to be excluded, such as moderate to severe degree of acute or chronic cardiac and pulmonary diseases, adrenal insufficiency, sarcopenia, obesity, malnutrition, and so on. The authors have to clarify the surveillance and exclusion criteria involved fatigue-related comorbidities.

Response:

Our previous response was:

'We agree and since fatigue can be multifactorial, we excluded patients who had obvious other reasons for fatigue than PBC and the most frequent reasons are now mentioned in the method section. In addition, the RCT design aim to equally distribute participants who might have other reasons for fatigue.'

We have nothing more to add. We excluded patients with obvious reasons for fatigue. A complete list for possible reasons for fatigue would be endless. As stated above, the randomisation process aims to equally distribute possible differences between groups.

Comment 3:

Patients' nutrition status (malnutrition, obesity, sarcopenia, etc.) and daily intake amount would have big impacts on fatigue score. The authors have to present the information about daily intake of calories and protein, the nutrition status of patients before and after thiamine supplementation as well.

Response:

As stated above, we excluded patients with obvious reasons for fatigue. This would also include malnutrition. However, no one showed sign of malnutrition or severe obesity. Mean BMI was between 27-29 (Table 1). We did not monitor daily nutrition intake. And as stated above, possible differences in nutrition intake would be equally distributed via randomisation.

Comment 4:

In patients with PBC, liver function has a great influence on the clinical fatigue of them. The authors also have to present the liver function of patients before and after thiamine supplementation.

Response:

Table 1 shows an equal distribution of patients between groups. This includes biochemistry.

Comment 5: There are some spelling mistakes that need to be corrected, such as the 3 impaired kidney fun"k"tion in figure 1.

Response:

Thank you. Good observation. Figure 1 has been updated.

Decision Letter 2

Wan-Long Chuang

15 Mar 2024

High-dose oral thiamine versus placebo for chronic fatigue in patients with primary biliary cholangitis: A crossover randomized clinical trial

PONE-D-23-41263R2

Dear Dr. Bager,

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Additional Editor Comments (optional):

The comments are well responded. The reason for "Reject" by Reviewer 1 is the limited number of the patients. However, Reviewer 2, an expert of statistical analysis, considered the study design and patients number are acceptable. In addition, there are no other comments by the 3 reviewers. So I think this manuscript could be accepted for publication.

Reviewers' comments:

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Reviewer #3: All comments have been addressed

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Reviewer #2: (No Response)

Reviewer #3: Yes

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Reviewer #2: (No Response)

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Reviewer #2: (No Response)

Reviewer #3: Yes

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Reviewer #1: The enrolled number of patients in this clinical study is not sufficient to draw solid conclusions.

Reviewer #2: (No Response)

Reviewer #3: All the comments have been answered well and the wrong spelling has been corrected.

I have no other comments to this study.

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Acceptance letter

Wan-Long Chuang

21 Mar 2024

PONE-D-23-41263R2

PLOS ONE

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