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Journal of Translational Medicine logoLink to Journal of Translational Medicine
. 2022 Jun 11;20:268. doi: 10.1186/s12967-022-03461-0

Treatments of chronic fatigue syndrome and its debilitating comorbidities: a 12-year population-based study

Kam-Hang Leong 1,2,#, Hei-Tung Yip 3,#, Chien-Feng Kuo 1,4,5,#, Shin-Yi Tsai 1,2,6,7,8,
PMCID: PMC9187893  PMID: 35690765

Abstract

Background

This study aims to provide 12-year nationwide epidemiology data to investigate the epidemiology and comorbidities of and therapeutic options for chronic fatigue syndrome (CFS) by analyzing the National Health Insurance Research Database.

Methods

6306 patients identified as having CFS during the 2000–2012 period and 6306 controls (with similar distributions of age and sex) were analyzed.

Result

The patients with CFS were predominantly female and aged 35–64 years in Taiwan and presented a higher proportion of depression, anxiety disorder, insomnia, Crohn’s disease, ulcerative colitis, renal disease, type 2 diabetes, gout, dyslipidemia, rheumatoid arthritis, Sjogren syndrome, and herpes zoster. The use of selective serotonin receptor inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), Serotonin antagonist and reuptake inhibitors (SARIs), Tricyclic antidepressants (TCAs), benzodiazepine (BZD), Norepinephrine-dopamine reuptake inhibitors (NDRIs), muscle relaxants, analgesic drugs, psychotherapies, and exercise therapies was prescribed significantly more frequently in the CFS cohort than in the control group.

Conclusion

This large national study shared the mainstream therapies of CFS in Taiwan, we noticed these treatments reported effective to relieve symptoms in previous studies. Furthermore, our findings indicate that clinicians should have a heightened awareness of the comorbidities of CFS, especially in psychiatric problems.

Keywords: Chronic fatigue syndrome, Epidemiology, Treatment, National health programs, Nationwide population-based study

Introduction

Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis, is characterized by the experience of debilitating fatigue for more than 6 months that is not improved by rest [1]. The World Health Organization classifies CFS as a neurological illness, and over the last 30 years, numerous studies have identified and verified the diagnostic criteria for CFS, which are unexplained persistent or relapsing fatigue lasting at least 6 months with the addition of the concurrent presence of four or more of the following symptoms over a 6-month period: unusual postexertion fatigue, impaired memory or concentration, unrefreshing sleep, headache, muscle pain, joint pain, sore throat, and tender cervical nodes [2].

Several studies have indicated that the following multifactorial mechanisms contribute to the onset of CFS: Epstein–Barr virus, human herpes virus 6 [3], Helicobacter pylori,[4] Mycobacterium tuberculosis infection [5], immunoinflammatory pathways [6], neuroimmune dysfunctions [7], and oxidative and nitrosative stress pathways, such as those induced by burn injury [8, 9]. It also shares some features of autoimmune disease. In addition, we previously reported that inflammatory bowel disease, herpes zoster and psoriasis are associated with an increased risk of subsequent CFS [1012].

CFS considerably reduces patients’ quality of life and places a financial burden on the patients, their families, and health care systems [13]. The primary goals of management are to relieve symptoms and provide supportive health care to improve functional capacities. However, no pharmaceutical therapies have been licensed for CFS nor has any strong evidence been revealed on the efficacy of a single regimen. In the present study, we investigated the epidemiology and comorbidities of and therapeutic options for CFS by using Taiwan’s National Health Insurance Research Database (NHIRD). Our results can help physicians diagnose CFS early and manage the disorder effectively.

Methods

Data source

The data set used in this study was derived from the NHIRD, which contains details concerning the demographic characteristics, dates of admission and discharge, drug prescriptions, surgical procedures, and diagnostic codes for approximately 99% of Taiwan’s population of 23 million. The 2000 Longitudinal Health Insurance Database, which is a data subset of the NHIRD, includes all the original claims data and registration files for 1 million individuals randomly sampled from among the beneficiaries of the NHI program in 2000 in Taiwan. The diseases are defined according to the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM).

Sample participants

Cases of CFS were identified using two outpatient records or one admission record with a diagnosis of ICD-9-CM code 780.71. The date of the first diagnosis of CFS was the index date. For each CFS case, we used a frequency matching method to select a participant without CFS with the same sex, age, and index date as a control. Participants aged below 18 years or with missing information on sex were excluded.

Exposure assessment and comorbidities

For this study, we examined exposure to pharmaceutical and nonpharmaceutical treatments. In terms of exposure to pharmaceutical treatments, we included the following: selective serotonin receptor inhibitors (SSRIs) (Anatomical Therapeutic Chemical (ATC) code N06AB10, N06AB06, N06AB03, N06AB08 and N06AB05), serotonin norepinephrine reuptake inhibitors (SNRIs) (ATC code N06AX21 and N06AX16), Serotonin antagonist and reuptake inhibitors (SARIs) (ATC code N06AX05), Tricyclic antidepressants (TCAs) (ATC code N06AA09 and N06CA01), benzodiazepine (BZD) (ATC code N03AE01, N05BA06, N05BA12, N05BA01, N05BA17, N05BA22, N05CD04, N05CD05, N05CD03, N05CD09, N05CD01 and N05CD08), Norepinephrine-dopamine reuptake inhibitors (NDRIs) (ATC code N06AX12), Noradrenergic and specific serotonergic antidepressants (NaSSAs) (ATC code N06AX11), muscle relaxants (ATC code M03BX08), and analgesic drugs (including acetaminophen, nonsteroidal anti-inflammatory drugs [NSAIDs], pregabalin, and gabapentin) (ATC code M02AA, D11AX18, M01A, M01B, N03AX16, and N03AX12). With regard to nonpharmaceutical treatments, we included supportive individual psychotherapy, supportive group psychotherapy, intensive individual psychotherapy, intensive group psychotherapy, reeducative individual psychotherapy, reeducative group psychotherapy, behavior modification assessments, behavior modification planning, stretching exercise, therapeutic exercise, breathing exercises, reconditioning exercise, multiple physical examinations of sleep, brainwave examination, sleep or wakefulness and a brainwave examination for sleep disorders. We made adjustments for the potentially confounding effects of other comorbidities, including depression(ICD-9-CM code 296.2, 296.3, 926.82, 300.4, 309.0, 309.1, and 311), anxiety disorder (ICD-9-CM code 300.0–300.3, 300.5–300.9, 309.2–309.4, 309.81, and 313.0), Insomnia (ICD-9-CM code 307.41, 307.42, 780.50, and 780.52), suicide (ICD-9-CM code E950-E959), crohn's disease (ICD-9-CM code 555), ulcerative colitis (ICD-9-CM code 555–556), renal disease (ICD-9-CM code 580–589), diabetes mellitus (ICD-9-CM code 250 and A181), obesity (ICD-9-CM code 278), gout (ICD-9-CM code 274), dyslipidemia (ICD-9-CM code 272), malignancy (ICD-9-CM code 140–208), HIV (ICD-9-CM code 042–044), rheumatoid arthritis (ICD-9-CM code 714), psoriasis (ICD-9-CM code 696.x), ankylosing spondylitis (ICD-9-CM code 720.0), lymphadenopathy (ICD-9-CM code 289.1–289.3, 686, and 785.6), Hashimoto’s thyroiditis (ICD-9-CM code 245.2), Sjogren’s syndrome (ICD-9-CM code 710.2), irritable bowel syndrome (ICD-9-CM code 564.1), SLE (ICD-9-CM code 710.0), celiac disease (ICD-9-CM code 579.00, fibromyalgia (ICD-9-CM 729.1), and herpes zoster (ICD-9-CM code 053) anxiety disorders, insomnia, suicide, Crohn disease, ulcerative colitis, and renal disease, prior to the index date. These were evaluated as part of the analysis.

Statistical analysis

The descriptive statistics of CFS and the controls were reported, including demographic characteristics, comorbid diseases, and treatments received after the index date. The chi-square test was used to compare categorical variables, and Student’s t-test was used to compare continuous variables between the CFS cohort and the control cohort, as necessary. We used a logistic regression model to assess the CFS treatments the patients had received. The odds ratio (OR) and 95% confidence intervals (CIs) were calculated and then subsequently adjusted using covariates, which included age, sex, and comorbidities. Analyses were performed using SAS software (version 9.4 for Windows; SAS Institute, Cary, NC, USA). Values were considered statistically significant at p < 0.05.

Results

Of the 1,000,000 patients in the LHID2000 database, 6850 patients were diagnosed with CFS. Among these patients, 6306 patients were newly diagnosed with CFS during the study period. In total, 12,612 participants were enrolled, including 6306 CFS patients and 6306 non-CFS patients (Fig. 1). The demographic and clinical characteristics of the study participants are presented in Table 1. The participants were predominantly female and aged 35–64 years. The mean (standard deviation) age was 50.6 years in both groups. Patients in the CFS group most presented with the comorbidities of depression, anxiety disorder, insomnia, Crohn’s disease, ulcerative colitis, renal disease, type 2 diabetes, gout, dyslipidemia, rheumatoid arthritis, Sjogren syndrome, and herpes zoster.

Fig. 1.

Fig. 1

The selection process of the participants in the cohort study

Table 1.

Demographic characteristics and comorbidities of patients newly diagnosed with chronic fatigue syndrome in Taiwan between 2000 and 2012 and of those in the control group

Variable CFS cohort Non-CFS cohort P-value
(n = 6306) (n = 6306)
Gender > 0.99
 Female 3339 (52.9) 3339 (52.9)
 Male 2967 (47.1) 2967 (47.1)
Age at diagnosis of CFS > 0.99
 ≤ 34 1350 (21.4) 1350 (21.4)
 35–64 3485 (55.3) 3485 (55.3)
 ≥ 65 1471 (23.3) 1471 (23.3)
Age at diagnosis of CFS(mean, SD)† 50.6 (17.9) 50.6 (18.0) 0.80
Comorbidity
 Depression 807 (12.8) 407 (6.45) < 0.0001
 Anxiety disorder 2038 (32.3) 1033 (16.4) < 0.0001
 Insomnia 2303 (36.5) 1106 (17.5) < 0.0001
 Suicide 19 (0.30) 12 (0.19) 0.20
 Crohn's disease 255 (4.04) 121 (1.92) < 0.0001
 Ulcerative colitis 279 (4.42) 138 (2.19) < 0.0001
 Renal disease 585 (9.28) 427 (6.77) < 0.0001
 T1DM 78 (1.24) 68 (1.08) 0.40
 T2DM 1473 (23.3) 1068 (16.9) < 0.0001
 Obesity 93 (1.47) 64 (1.01) 0.01
 Gout 1196 (18.9) 702 (11.1) < 0.0001
 Dyslipidemia 2252 (35.7) 1356 (21.5) < 0.0001
 Malignancy 407 (6.45) 487 (7.72) 0.01
 HIV 3 (0.05) 3 (0.05) > 0.99
 Rheumatoid arthritis 254 (4.03) 155 (2.46) < 0.0001
 Psoriasis 94 (1.49) 83 (1.32) 0.40
 Ankylosing spondylitis 53 (0.84) 39 (0.62) 0.14
 Lymphadenopathy 132 (2.09) 104 (1.65) 0.06
 Hashimoto's thyroiditis 13 (0.21) 10 (0.16) 0.53
 Sjogren's syndrome 110 (1.74) 71 (1.13) 0.003
 Irritable bowel syndrome 886 (14.1) 423 (6.71) < 0.0001
 Fibromyalgia 4905 (77.8) 4914 (77.9) 0.85
 SLE 4 (0.06) 9 (0.14) 0.16
 Herpes zoster 341 (5.41) 234 (3.71) < 0.0001

Table 2 lists the treatments received by both the patients with CFS and those without. With adjustments for sex, age, and comorbidities, patients with CFS had higher odds of receiving SSRIs (adjusted OR [aOR] = 1.70; 95% CI 1.48, 1.95), SNRIs (adjusted OR [aOR] = 1.52; 95% CI 1.20, 1.93), SARIs (aOR = 1.56; 95% CI 1.35, 1.78), TCAs (aOR = 1.37; 95% CI 1.07, 1.76), BZD (aOR = 1.70; 95% CI 1.57, 1.84), NDRI (aOR = 1.59; 95% CI 1.08, 2.36), Muscle relaxant (aOR = 1.52; 95% CI 1.24, 1.86) and Analgesic drug (aOR = 9.55; 95% CI 7.72, 11.81) than patients without CFS. Moreover, psychotherapy, including supportive individual psychotherapy (aOR = 1.28; 95% CI 1.09, 1.51), intensive individual psychotherapy (aOR = 2.73; 95% CI 1.47, 5.04), reeducative individual psychotherapy (aOR = 1.31; 95% CI 1.11, 1.56), stretching exercises (aOR = 1.26; 95% CI 1.10, 1.45), therapeutic exercise (aOR = 1.33; 95% CI 1.19, 1.47), and a brainwave examination for sleep disorders (20001C, 20002C; aOR = 1.40; 95% CI 1.25, 1.55) were frequently prescribed to patients with CFS. Figure 2 demonstrated the cumulative incidence calculated as the number of new patients who received nonpharmaceutical treatment divided by the total number of CFS patients who were at risk and multiple by 100. In 6850 CFS patients, the highest cumulative incidences of treatment were therapeutic exercise (14.95%), followed by brainwave examination for sleep disorders (11.58%) and stretching exercise (9.49%).

Table 2.

 Odds ratios for various treatments for patients with and without chronic fatigue syndrome

Variable N Control CFS Odds ratio
n % n % Crude (95% CI) p-value Adjusted (95% CI) p-value
SSRI 2.33 (2.05,2.66)*** < 0.001 1.70 (1.48,1.95)*** < 0.001
 No 11,471 5946 52 5525 48
 Yes 1141 360 32 781 68
SNRI 2.22 (1.77,2.78)*** < 0.001 1.52 (1.20,1.93)*** < 0.001
 No 12,260 6195 51 6065 49
 Yes 352 111 32 241 68
SARI 2.21 (1.95,2.52)*** < 0.001 1.56 (1.35,1.78)*** < 0.001
 No 11,451 5927 52 5524 48
 Yes 1161 379 33 782 67
TCAs 1.79 (1.42,2.28)*** < 0.001 1.37 (1.07,1.76)* 0.01
 No 12,310 6197 50 6113 50
 Yes 302 109 36 193 64
BZD 2.13 (1.98,2.29)*** < 0.001 1.70 (1.57,1.84)*** < 0.001
 No 5368 3260 61 2108 39
 Yes 7244 3046 42 4198 58
NDRI 2.42 (1.67,3.51)*** < 0.001 1.59 (1.08,2.36)* 0.02
 No 12,476 6266 50 6210 50
 Yes 136 40 29 96 71
NaSSA 2.02 (1.57,2.59)*** < 0.001 1.28 (0.98,1.67) 0.08
 No 12,331 6212 50 6119 50
 Yes 281 94 33 187 67
Muscle relaxant 1.80 (1.49,2.19)*** < 0.001 1.52 (1.24,1.86)*** < 0.001
 No 12,150 6139 51 6011 49
 Yes 462 167 36 295 64
Analgesic drug 12.44 (10.12,15.3)*** < 0.001 9.55 (7.72,11.81)*** < 0.001
 No 1173 1071 91 102 9
 Yes 11,439 5235 46 6204 54
Supportive individual psychotherapy 1.90 (1.63,2.21)*** < 0.001 1.28 (1.09,1.51)** 0.003
 No 11,837 6032 51 5805 49
 Yes 775 274 35 501 65
Supportive group psychotherapy 2.29 (1.52,3.45)*** < 0.001 1.52 (0.99,2.35) 0.057
 No 12,504 6273 50 6231 50
 Yes 108 33 31 75 69
Intensive individual psychotherapy 3.95 (2.20,7.12)*** < 0.001 2.73 (1.47,5.04)** 0.001
 No 12,543 6292 50 6251 50
 Yes 69 14 20 55 80
Intensive group psychotherapy 2.13 (0.92,4.93) 0.078 1.57 (0.65,3.78) 0.318
 No 12,587 6298 50 6289 50
 Yes 25 8 32 17 68
Re-educative individual psychotherapy 2.01 (1.72,2.36)*** < 0.001 1.31 (1.11,1.56)** 0.002
 No 11,881 6057 51 5824 49
 Yes 731 249 34 482 66
Re-educative group psychotherapy 2.30 (1.37,3.84)** 0.002 1.49 (0.87,2.56) 0.149
 No 12,543 6285 50 6258 50
 Yes 69 21 30 48 70
Behavior modification assessment
 No 12,612 6306 50 6306 50
 Yes 0 0 0 0 0
Behavior modification planning 1.60 (1.02,2.54)* 0.043 1.15 (0.71,1.86) 0.582
 No 12,534 6276 50 6258 50
 Yes 78 30 38 48 62
Stretching exercise 1.44 (1.26,1.64)*** < 0.001 1.26 (1.10,1.45)*** < 0.001
 No 11,600 5884 51 5716 49
 Yes 1012 422 42 590 58
Therapeutic exercise 1.47 (1.33,1.63)*** < 0.001 1.33 (1.19,1.47)*** < 0.001
 No 10,768 5535 51 5233 49
 Yes 1844 771 42 1073 58
Breathing exercise 1.04 (0.82,1.32) 0.758 0.92 (0.71,1.18) 0.506
 No 12,343 6174 50 6169 50
 Yes 269 132 49 137 51
Reconditioning exercise 1.30 (0.94,1.79) 0.108 1.19 (0.85,1.67) 0.310
 No 12,456 6238 50 6218 50
 Yes 156 68 44 88 56
Multiple physical examinations of sleep 1.48 (1.10,2.00)* 0.011 1.07 (0.78,1.47) 0.676
 No 12,434 6234 50 6200 50
 Yes 178 72 40 106 60
Brainwave examination, sleep or wakefulness 1.60 (1.44,1.77)*** < 0.001 1.40 (1.25,1.55)*** < 0.001
 No 10,825 5590 52 5235 48
 Yes 1787 716 40 1071 60
Brainwave examination for sleep disorders
 No 12,612 6306 50 6306 50
 Yes 0 0 0 0 0

CFS: chronic fatigue syndrome; N: total number of subjects the subgroups; n: number of subjects; CI: confidence interval; SSRI: selective serotonin receptor inhibitors; SNRI: serotonin norepinephrine Reuptake Inhibitors; SARI: serotonin antagonist and reuptake inhibitors; TCAs: tricyclic antidepressant; MAOi: Monoamine oxidase inhibitors; BZD: benzodiazepine; *P < .05, **P < .01, ***P < .001

Fig. 2.

Fig. 2

Cumulative incidences of different nonpharmaceutical treatment among the CFS subpopulations

The stratification of treatments for patients with CFS in terms of depression, anxiety disorders, and insomnia is presented in Table 3. For patients with depression, those with CFS were more likely to receive SSRIs, SNRIs, SARIs, BZD, analgesic drugs, reeducative individual psychotherapy and therapeutic exercise. SSRIs, SNRIs, SARIs, BZD, NDRI, analgesic drugs, muscle relaxants, reeducative individual psychotherapy stretching exercise and therapeutic exercise were commonly prescribed for patients with CFS identified with an anxiety disorder. In the subgroup of patients with insomnia, SSRIs, SNRIs, SARIs, BZD, analgesic drugs, reeducative individual psychotherapy and therapeutic exercise were most prescribed to patients with CFS.

Table 3.

The odd ratios of treatments for patients with and without chronic fatigue syndrome in difference subgroup of comorbidities

Variable Control
(n = 6306)
CFS
(n = 6306)
Odds ratio
Crude (95% CI) p-value Adjusted (95% CI) p-value
Depression
No Yes No Yes
SSRI 1.69 (1.29,2.22)*** < 0.001 1.52 (1.14,2.03)** 0.004
 No 5633 313 4990 535
 Yes 266 94 509 272
SNRI 2.72 (1.67,4.42)*** < 0.001 2.56 (1.55,4.23)*** < 0.001
 No 5809 386 5362 703
 Yes 90 21 137 104
SARI 1.91 (1.43,2.54)*** < 0.001 1.73 (1.28,2.36)*** < 0.001
 No 5599 328 4971 553
 Yes 300 79 528 254
TCAs 1.30 (0.78,2.17) 0.305 1.21 (0.71,2.08) 0.480
 No 5812 385 5362 751
 Yes 87 22 137 56
BZD 1.96 (1.42,2.71)*** < 0.001 1.77 (1.24,2.52)** 0.002
 No 3178 82 2016 92
 Yes 2721 325 3483 715
NDRI 1.75 (0.93,3.28) 0.083 1.60 (0.82,3.09) 0.167
 No 5872 394 5447 763
 Yes 27 13 52 44
Muscle relaxant 1.58 (0.92,2.73) 0.100 1.27 (0.72,2.25) 0.411
 No 5750 389 5259 752
 Yes 149 18 240 55
Analgesic drug 13.7 (6.41,29.15)*** < 0.001 11.15 (5.00,24.87)*** < 0.001
 No 1022 49 94 8
 Yes 4877 358 5405 799
Supportive individual psychotherapy 1.52 (1.13,2.04)** 0.006 1.27 (0.92,1.74) 0.142
 No 5700 332 5204 601
 Yes 199 75 295 206
Intensive individual psychotherapy 1.94 (0.72,5.23) 0.191 1.79 (0.58,5.46) 0.310
 No 5890 402 5463 788
 Yes 9 5 36 19
Re-educative individual psychotherapy 1.72 (1.28,2.31)*** < 0.001 1.50 (1.10,2.05)* 0.011
 No 5724 333 5240 584
 Yes 175 74 259 223
Stretching exercise 1.12 (0.77,1.64) 0.538 1.12 (0.76,1.66) 0.563
 No 5522 362 5008 708
 Yes 377 45 491 99
Therapeutic exercise 1.80 (1.30,2.50)*** < 0.001 1.81 (1.29,2.55)*** < 0.001
 No 5184 351 4606 627
 Yes 715 56 893 180
Brainwave examination, sleep or wakefulness 1.01 (0.45,2.27) 0.983 0.98 (0.42,2.30) 0.959
 No 5776 398 5380 789
 Yes 123 9 119 18
Variable Control CFS Odds ratio
Crude (95% CI) p-value Adjusted (95% CI) p-value
Anxiety disorder
No Yes No Yes
SSRI 1.70 (1.38,2.09)*** < 0.001 1.54 (1.24,1.92)*** < 0.001
 No 5054 892 3918 1607
 Yes 219 141 350 431
SNRI 2.41 (1.63,3.57)*** < 0.001 2.02 (1.35,3.03)*** < 0.001
 No 5194 1001 4173 1892
 Yes 79 32 95 146
SARI 1.60 (1.31,1.96)*** < 0.001 1.37 (1.11,1.7)** 0.004
 No 5045 882 3925 1599
 Yes 228 151 343 439
TCAs 1.25 (0.86,1.83) 0.238 1.14 (0.77,1.68) 0.508
 No 5204 993 4173 1940
 Yes 69 40 95 98
BZD 1.89 (1.56,2.29)*** < 0.001 1.68 (1.37,2.06)*** < 0.001
 No 3022 238 1829 279
 Yes 2251 795 2439 1759
NDRI 2.09 (1.21,3.64)** 0.009 1.84 (1.04,3.25)* 0.037
 No 5249 1017 4237 1973
 Yes 24 16 31 65
Muscle relaxant 1.57 (1.09,2.25)* 0.015 1.46 (1.01,2.11)* 0.046
 No 5147 992 4097 1914
 Yes 126 41 171 124
Analgesic drug 7.84 (4.7,13.09)*** < 0.001 7.80 (4.55,13.38)*** < 0.001
 No 1000 71 83 19
 Yes 4273 962 4185 2019
Supportive individual psychotherapy 1.37 (1.09,1.72)** 0.007 1.15 (0.9,1.47) 0.267
 No 5113 919 4063 1742
 Yes 160 114 205 296
Intensive individual psychotherapy 2.34 (1.03,5.31)* 0.043 1.87 (0.79,4.46) 0.155
 No 5266 1026 4245 2006
 Yes 7 7 23 32
Re-educative individual psychotherapy 1.58 (1.25,2.00)*** < 0.001 1.34 (1.04,1.73)* 0.025
 No 5128 929 4092 1732
 Yes 145 104 176 306
Stretching exercise 1.49 (1.15,1.93)** 0.003 1.44 (1.1,1.88)** 0.008
 No 4936 948 3918 1798
 Yes 337 85 350 240
Therapeutic exercise 1.32 (1.08,1.61)** 0.006 1.29 (1.05,1.58)* 0.016
 No 4669 866 3609 1624
 Yes 604 167 659 414
Brainwave examination, sleep or wakefulness 0.69 (0.44,1.09) 0.109 0.67 (0.42,1.07) 0.095
 No 5175 999 4178 1991
 Yes 98 34 90 47
Variable Control CFS Odds ratio
Crude (95% CI) p-value Adjusted (95% CI) p-value
Insomnia
No Yes No Yes
SSRI 1.81 (1.47,2.24)*** < 0.001 1.65 (1.32,2.06)*** < 0.001
 No 4969 977 3667 1858
 Yes 231 129 336 445
SNRI 1.74 (1.23,2.47)** 0.002 1.54 (1.07,2.21)* 0.019
 No 5131 1064 3910 2155
 Yes 69 42 93 148
SARI 1.45 (1.2,1.76)*** < 0.001 1.30 (1.06,1.59)* 0.011
 No 4991 936 3701 1823
 Yes 209 170 302 480
TCAs 1.62 (1.09,2.4)* 0.018 1.58 (1.05,2.38)* 0.027
 No 5124 1073 3919 2194
 Yes 76 33 84 109
BZD 1.43 (1.2,1.71)*** < 0.001 1.37 (1.14,1.66)** 0.001
 No 3008 252 1714 394
 Yes 2192 854 2289 1909
NDRI 2.01 (1.14,3.55)* 0.016 1.75 (0.97,3.16) 0.062
 No 5175 1091 3969 2241
 Yes 25 15 34 62
Muscle relaxant 1.19 (0.86,1.65) 0.285 1.11 (0.80,1.55) 0.530
 No 5087 1052 3841 2170
 Yes 113 54 162 133
Analgesic drug 8.75 (5.77,13.25)*** < 0.001 8.00 (5.16,12.4)*** < 0.001
 No 960 111 73 29
 Yes 4240 995 3930 2274
Supportive individual psychotherapy 1.26 (1.01,1.59)* 0.044 1.03 (0.81,1.32) 0.784
 No 5042 990 3799 2006
 Yes 158 116 204 297
Intensive individual psychotherapy 1.63 (0.74,3.6) 0.228 1.31 (0.57,3.02) 0.519
 No 5194 1098 3975 2276
 Yes 6 8 28 27
Re-educative individual psychotherapy 1.57 (1.24,2)*** < 0.001 1.35 (1.04,1.74)* 0.024
 No 5049 1008 3826 1998
 Yes 151 98 177 305
Stretching exercise 1.30 (1.02,1.66)* 0.033 1.26 (0.99,1.62) 0.064
 No 4878 1006 3677 2039
 Yes 322 100 326 264
Therapeutic exercise 1.52 (1.25,1.84)*** < 0.001 1.52 (1.25,1.86)*** < 0.001
 No 4591 944 3406 1827
 Yes 609 162 597 476
Brainwave examination, sleep or wakefulness 0.84 (0.56,1.26) 0.405 0.88 (0.58,1.33) 0.539
 No 5106 1068 3933 2236
 Yes 94 38 70 67

CFS: chronic fatigue syndrome; CI: confidence interval; *P < .05, **P < .01, ***P < .001

As presented in Table 4, patients with CFS were more likely to receive SSRIs, BZD and analgesic drugs in each age group. The odds of patients with CFS aged 35–64 and ≥ 65 receiving SARIs and muscle relaxant treatments were higher than the odds of those without CFS. For participants aged 35–64 years, reeducative individual psychotherapy was also frequently received by patients with CFS. Female and male patients with CFS were equally likely to be treated with SSRIs, SNRIs, SARIs, BZD, muscle relaxants, analgesic drugs, reeducative individual psychotherapy, intensive individual psychotherapy and therapeutic exercise, TCAs was higher prescribed to female and NDRI was higher used in male, as presented in Table 5.

Table 4.

The odd ratios of treatments for patients with and without chronic fatigue syndrome in difference subgroup of age

Variable Control
(n = 6306)
CFS
(n = 6306)
Odds ratio
Age ≤ 34 y/o Crude (95% CI) p-value Adjusted (95% CI) p-value
No Yes No Yes
SSRI 1.98 (1.43,2.74)*** < 0.001 1.53 (1.08,2.15)* 0.015
 No 4758 1188 4386 1139
 Yes 300 60 667 114
SNRI 2.13 (1.23,3.7)** 0.007 1.39 (0.77,2.52) 0.272
 No 4966 1229 4852 1213
 Yes 92 19 201 40
SARI 1.82 (1.25,2.65)** 0.002 1.20 (0.8,1.8) 0.375
 No 4724 1203 4351 1173
 Yes 334 45 702 80
TCAs 2.17 (1.12,4.21)* 0.022 1.59 (0.78,3.22) 0.2
 No 4962 1235 4888 1225
 Yes 96 13 165 28
BZD 1.91 (1.62,2.25)*** < 0.001 1.61 (1.36,1.92)*** < 0.001
 No 2380 880 1411 697
 Yes 2678 368 3642 556
NDRI 2.29 (0.94,5.59) 0.068 1.34 (0.5,3.56) 0.557
 No 5025 1241 4973 1237
 Yes 33 7 80 16
Muscle relaxant 1.88 (1.1,3.21)* 0.021 1.69 (0.97,2.96) 0.065
 No 4912 1227 4797 1214
 Yes 146 21 256 39
Analgesic drug 3.94 (2.57,6.02)*** < 0.001 3.89 (2.49,6.06)*** < 0.001
 No 968 103 74 28
 Yes 4090 1145 4979 1225
Supportive individual psychotherapy 1.74 (1.23,2.45)** 0.002 1.13 (0.77,1.64) 0.531
 No 4839 1193 4645 1160
 Yes 219 55 408 93
Intensive individual psychotherapy 5.37 (1.56,18.47)** 0.008 3.34 (0.92,12.17) 0.067
 No 5047 1245 5014 1237
 Yes 11 3 39 16
Re-educative individual psychotherapy 1.85 (1.29,2.65)*** < 0.001 1.20 (0.81,1.79) 0.362
 No 4858 1199 4659 1165
 Yes 200 49 394 88
Stretching exercise 1.21 (0.86,1.70) 0.274 1.15 (0.81,1.63) 0.425
 No 4701 1183 4541 1175
 Yes 357 65 512 78
Therapeutic exercise 1.08 (0.84,1.39) 0.544 0.98 (0.76,1.28) 0.89
 No 4418 1117 4121 1112
 Yes 640 131 932 141
Brainwave examination, sleep or wakefulness 0.63 (0.24,1.64) 0.344 0.60 (0.22,1.65) 0.321
 No 4937 1237 4923 1246
 Yes 121 11 130 7
Variable Control
(n = 6306)
CFS
(n = 6306)
Odds ratio
Age 35–64 y/o Crude (95% CI) p-value Adjusted (95% CI) p-value
No Yes No Yes
SSRI 2.15 (1.85,2.50)*** < 0.001 1.57 (1.34,1.85)*** < 0.001
 No 1389 4557 1251 4274
 Yes 82 278 220 561
SNRI 2.23 (1.71,2.90)*** < 0.001 1.56 (1.18,2.07)** 0.002
 No 1443 4752 1411 4654
 Yes 28 83 60 181
SARI 2.19 (1.88,2.55)*** < 0.001 1.53 (1.3,1.81)*** < 0.001
 No 1356 4571 1232 4292
 Yes 115 264 239 543
TCAs 2.09 (1.57,2.79)*** < 0.001 1.66 (1.22,2.24)** 0.001
 No 1432 4765 1422 4691
 Yes 39 70 49 144
BZD 2.15 (1.98,2.33)*** < 0.001 1.71 (1.56,1.87)*** < 0.001
 No 474 2786 236 1872
 Yes 997 2049 1235 2963
NDRI 2.19 (1.46,3.3)*** < 0.001 1.52 (0.99,2.35) 0.057
 No 1465 4801 1449 4761
 Yes 6 34 22 74
Muscle relaxant 1.73 (1.38,2.18)*** < 0.001 1.46 (1.14,1.85)** 0.002
 No 1424 4715 1380 4631
 Yes 47 120 91 204
Analgesic drug 9.18 (7.27,11.59)*** < 0.001 6.83 (5.38,8.66)*** < 0.001
 No 410 661 20 82
 Yes 1061 4174 1451 4753
Supportive individual psychotherapy 1.82 (1.53,2.16)*** < 0.001 1.20 (1,1.45) 0.054
 No 1415 4617 1352 4453
 Yes 56 218 119 382
Intensive individual psychotherapy 4.11 (2.19,7.75)*** < 0.001 2.95 (1.52,5.73)** 0.001
 No 1469 4823 1465 4786
 Yes 2 12 6 49
Re-educative individual psychotherapy 2.01 (1.68,2.39)*** < 0.001 1.33 (1.1,1.61)** 0.004
 No 1423 4634 1376 4448
 Yes 48 201 95 387
Stretching exercise 1.43 (1.23,1.67)*** < 0.001 1.27 (1.08,1.49)** 0.004
 No 1360 4524 1315 4401
 Yes 111 311 156 434
Therapeutic exercise 1.42 (1.26,1.59)*** < 0.001 1.28 (1.13,1.45)*** < 0.001
 No 1256 4279 1150 4083
 Yes 215 556 321 752
Brainwave examination, sleep or wakefulness 1.08 (0.79,1.50) 0.622 0.98 (0.69,1.37) 0.889
 No 1411 4763 1412 4757
 Yes 60 72 59 78
Variable Control
(n = 6306)
CFS
(n = 6306)
Odds ratio
Age ≥ 65 y/o Crude (95% CI) p-value Adjusted (95% CI) p-value
No Yes No Yes
SSRI 2.98 (2.29,3.88)*** < 0.001 2.17 (1.64,2.88)*** < 0.001
 No 4557 1389 4274 1251
 Yes 278 82 561 220
SNRI 2.19 (1.39,3.45)*** < 0.001 1.46 (0.9,2.37) 0.121
 No 4752 1443 4654 1411
 Yes 83 28 181 60
SARI 2.29 (1.81,2.89)*** < 0.001 1.69 (1.31,2.17)*** < 0.001
 No 4571 1356 4292 1232
 Yes 264 115 543 239
TCAs 1.27 (0.83,1.94) 0.28 0.89 (0.56,1.42) 0.633
 No 4765 1432 4691 1422
 Yes 70 39 144 49
BZD 2.49 (2.08,2.97)*** < 0.001 1.72 (1.42,2.09)*** < 0.001
 No 2786 474 1872 236
 Yes 2049 997 2963 1235
NDRI 3.71 (1.5,9.17)** 0.005 2.33 (0.9,6.03) 0.082
 No 4801 1465 4761 1449
 Yes 34 6 74 22
Muscle relaxant 2.00 (1.39,2.86)*** < 0.001 1.75 (1.2,2.56)** 0.004
 No 4715 1424 4631 1380
 Yes 120 47 204 91
Analgesic drug 28.0 (17.77,44.22)*** < 0.001 27.1 (16.65,44.03)*** < 0.001
 No 661 410 82 20
 Yes 4174 1061 4753 1451
Supportive individual psychotherapy 2.22 (1.6,3.08)*** < 0.001 1.58 (1.11,2.24)* 0.01
 No 4617 1415 4453 1352
 Yes 218 56 382 119
Intensive individual psychotherapy 3.01 (0.61,14.93) 0.178 1.47 (0.26,8.18) 0.662
 No 4823 1469 4786 1465
 Yes 12 2 49 6
Re-educative individual psychotherapy 2.05 (1.44,2.92)*** < 0.001 1.28 (0.87,1.88) 0.207
 No 4634 1423 4448 1376
 Yes 201 48 387 95
Stretching exercise 1.45 (1.13,1.88)** 0.004 1.29 (0.99,1.69) 0.063
 No 4524 1360 4401 1315
 Yes 311 111 434 156
Therapeutic exercise 1.63 (1.35,1.97)*** < 0.001 1.48 (1.21,1.82)*** < 0.001
 No 4279 1256 4083 1150
 Yes 556 215 752 321
Brainwave examination, sleep or wakefulness 0.98 (0.68,1.42) 0.925 0.86 (0.58,1.27) 0.447
 No 4763 1411 4757 1412
 Yes 72 60 78 59

CFS: chronic fatigue syndrome; CI: confidence interval; *:p-value; *P < .05, **P < .01, ***P < .001

Table 5.

The odd ratios of treatments for patients with and without chronic fatigue syndrome in difference subgroup of sex

Variable Control
(n = 6306)
CFS
(n = 6306)
Odds ratio
Female Crude (95% CI) p-value Adjusted (95% CI) p-value
No Yes No Yes
SSRI 2.36 (1.99,2.81)*** < 0.001 1.71 (1.42,2.06)*** < 0.001
 No 2815 3131 2639 2886
 Yes 152 208 328 453
SNRI 2.04 (1.51,2.75)*** < 0.001 1.42 (1.04,1.95)* 0.029
 No 2922 3273 2858 3207
 Yes 45 66 109 132
SARI 2.10 (1.77,2.5)*** < 0.001 1.46 (1.21,1.76)*** < 0.001
 No 2805 3122 2611 2913
 Yes 162 217 356 426
TCAs 2.25 (1.62,3.13)*** < 0.001 1.69 (1.2,2.38)** 0.003
 No 2911 3286 2891 3222
 Yes 56 53 76 117
BZD 2.22 (2.01,2.46)*** < 0.001 1.71 (1.53,1.92)*** < 0.001
 No 1663 1597 1133 975
 Yes 1304 1742 1834 2364
NDRI 2.16 (1.28,3.63)** 0.004 1.39 (0.8,2.4) 0.241
 No 2948 3318 2916 3294
 Yes 19 21 51 45
Muscle relaxant 1.89 (1.45,2.45)*** < 0.001 1.52 (1.15,2.01)** 0.003
 No 2889 3250 2836 3175
 Yes 78 89 131 164
Analgesic drug 13.54 (9.80,18.7)*** < 0.001 10.11 (7.26,14.09)*** < 0.001
 No 590 481 61 41
 Yes 2377 2858 2906 3298
Supportive individual psychotherapy 1.74 (1.42,2.13)*** < 0.001 1.19 (0.96,1.48) 0.121
 No 2851 3181 2731 3074
 Yes 116 158 236 265
Intensive individual psychotherapy 4.03 (1.85,8.76)*** < 0.001 2.76 (1.21,6.3)* 0.016
 No 2961 3331 2944 3307
 Yes 6 8 23 32
Re-educative individual psychotherapy 1.98 (1.61,2.44)*** < 0.001 1.26 (1.01,1.59)* 0.045
 No 2860 3197 2755 3069
 Yes 107 142 212 270
Stretching exercise 1.49 (1.26,1.77)*** < 0.001 1.30 (1.09,1.56)** 0.004
 No 2787 3097 2726 2990
 Yes 180 242 241 349
Therapeutic exercise 1.39 (1.22,1.59)*** < 0.001 1.24 (1.07,1.43)** 0.003
 No 2637 2898 2477 2756
 Yes 330 441 490 583
Brainwave examination, sleep or wakefulness 1.42 (0.99,2.04) 0.057 1.18 (0.81,1.74) 0.393
 No 2886 3288 2902 3267
 Yes 81 51 65 72
Variable Control
(n = 6306)
CFS
(n = 6306)
Odds ratio
Male Crude (95% CI) p-value Adjusted (95% CI) p-value
No Yes No Yes
SSRI 2.3 (1.89,2.81)*** < 0.001 1.70 (1.37,2.10)*** < 0.001
 No 3131 2815 2886 2639
 Yes 208 152 453 328
SNRI 2.48 (1.74,3.52)*** < 0.001 1.64 (1.13,2.38)** 0.009
 No 3273 2922 3207 2858
 Yes 66 45 132 109
SARI 2.36 (1.95,2.86)*** < 0.001 1.71 (1.38,2.10)*** < 0.001
 No 3122 2805 2913 2611
 Yes 217 162 426 356
TCAs 1.37 (0.96,1.94) 0.079 1.06 (0.73,1.53) 0.771
 No 3286 2911 3222 2891
 Yes 53 56 117 76
BZD 2.06 (1.86,2.29)*** < 0.001 1.69 (1.50,1.90)*** < 0.001
 No 1597 1663 975 1133
 Yes 1742 1304 2364 1834
NDRI 2.71 (1.60,4.61)*** < 0.001 1.81 (1.03,3.17)* 0.039
 No 3318 2948 3294 2916
 Yes 21 19 45 51
Muscle relaxant 1.71 (1.29,2.28)*** < 0.001 1.53 (1.13,2.07)** 0.005
 No 3250 2889 3175 2836
 Yes 89 78 164 131
Analgesic drug 11.82 (9.03,15.47)*** < 0.001 9.40 (7.11,12.43)*** < 0.001
 No 481 590 41 61
 Yes 2858 2377 3298 2906
Supportive individual psychotherapy 2.12 (1.69,2.67)*** < 0.001 1.38 (1.08,1.77)* 0.012
 No 3181 2851 3074 2731
 Yes 158 116 265 236
Intensive individual psychotherapy 3.86 (1.57,9.48)** 0.003 2.56 (1.00,6.57) 0.051
 No 3331 2961 3307 2944
 Yes 8 6 32 23
Re-educative individual psychotherapy 2.06 (1.62,2.61)*** < 0.001 1.39 (1.07,1.80)* 0.014
 No 3197 2860 3069 2755
 Yes 142 107 270 212
Stretching exercise 1.37 (1.12,1.67)** 0.002 1.21 (0.98,1.49) 0.081
 No 3097 2787 2990 2726
 Yes 242 180 349 241
Therapeutic exercise 1.58 (1.36,1.84)*** < 0.001 1.44 (1.23,1.69)*** < 0.001
 No 2898 2637 2756 2477
 Yes 441 330 583 490
Brainwave examination, sleep or wakefulness 0.8 (0.57,1.11) 0.181 0.75 (0.53,1.07) 0.117
 No 3288 2886 3267 2902
 Yes 51 81 72 65

CFS: chronic fatigue syndrome; CI: confidence interval;*P < .05, **P < .01, ***P < .001

Discussion

Our nationwide population-based study revealed that patients with CFS experienced more comorbidities, such as psychiatric problems (depression, anxiety disorders, and insomnia), autoimmune diseases (Crohn disease, ulcerative colitis, rheumatoid arthritis, and Sjogren syndrome), type 2 diabetes, renal diseases, and malignancy, than the participants without CFS. In addition, we found that the use of SSRIs, SARIs, SNRIs, TCAs, NDRI, BZD, muscle relaxants, analgesic drugs, psychotherapies and exercise therapies were higher in the CFS cohort. This finding is consistent with the general treatment for CFS [14]. Notably, brainwave examination is not a standard examination method for diagnosing CFS, but it was regularly used by clinicians in our study.

The etiology of CFS remains unknown. Emerging research suggests CFS is an autoimmune disease, with evidence of dysregulation of the immune and autonomic nervous systems as well as metabolic disturbances, triggered particularly by infection with stress [15]. Patients with CFS have been identified as having increased levels of autoantibodies against ß2-adrenergic receptors and M3 acetylcholine receptors [16]. The hypothalamic–pituitary–adrenal (HPA) axis maintains homeostasis through a self-regulating feedback system that helps to manage stress [17, 18], and abnormalities in the HPA axis are believed to be a feature of CFS [19]. In addition, we previously reported that psoriasis and inflammatory bowel disease significantly increased the risk of CFS [10, 11]. In future studies, the aspects of CFS linked to autoimmune diseases should be clarified.

In recent 2 years during COVID-19 pandemic, many studies indicated that some COVID-19 patients had persistent clinical signs and symptoms including fatigue, breathlessness, and cognitive dysfunction after recovering from initial illness. This condition named Post COVID-19 Syndrome or long COVID. Pathological inflammation with immune dysfunction was a one of the underlying multifactorial mechanism of long COVID, which was similar to CFS [2022]. Various autoantibodies were found in 10–50% of patients with COVID-19 [23]. These autoantibodies and increased levels of pro-inflammatory markers contributed to the disease severity and inflammation-related symptoms such as fatigue and joint pain [22, 24]. The treatments of CFS were believed to have a potential effect of relieving fatigue in long COVID cases [22, 25]. Future studies should be conducted to determine the underlying mechanism and treatments between CFS and long COVID.

Our comparison of patients with CFS with those without demonstrated that the use of SSRIs, SNRIs, SARIs and BZD was higher in the CFS cohort after adjustments for age, sex, and comorbidities (Table 2), especially in those with psychiatric problems (depression, anxiety disorders, and insomnia; Table 3). However, a subclassification analysis of age and sex established no significant differences between the two groups (Tables 4 and 5). Patients with CFS have been reported to have clinical depression and anxiety [26], and several pathophysiologies related to depression have been reported, such as inflammation with elevated cytokine levels (e.g., interleukin [IL]-1, tumor necrosis factor alpha [TNF-α]), increased oxidative stress, and decreased neurotrophic factors and brain neurotransmitters [27]. Serotonin (or 5-hydroxytryptamine 1A [5-HT1A]), a monoamine neurotransmitter, has been discovered to be linked to mood, behavior, sleep cycles, and appetite [28]. One study indicated that the number of brain 5-HT1A receptors was decreased in patients with CFS, with the decrease particularly marked in the bilateral hippocampus [29]. Furthermore, changes in the HPA axis in chronic stress were reported to be associated with the serotonin system and abnormal adrenocortical activity and were observed in patients with CFS [30]. One study indicated that patients with CFS prescribed SSRIs had a faster rate of recovery and experienced a greater reduction in fatigue levels than untreated patients [31]. However, few clinical trials have been conducted on CFS treatments, although the use of SSRIs for fibromyalgia, especially for patients with depression, may be advantageous for CFS [32]. Bupropion, a norepinephrine-dopamine reuptake inhibitor (NDRI), was reported to improve hypersomnia and fatigue significantly in the patients with major depressive disorder compared with the placebo-group [33]. Unrefreshing sleep is one feature of CFS, Cognitive-behavioral therapy for insomnia (CBT-I) and sleep hygiene education should be applied whenever possible [34]. Experienced clinicians believed that low-dose TCAs and BZD may also be useful for sleep. However, monitoring the adverse effects including drowsiness upon awakening must be considered.

Treatments for pain symptoms, including muscle relaxants and analgesic drugs, were more common among the CFS cohort (Table 2), but no significant difference in psychiatric comorbidities, age, or sex was identified in the subclassification analysis (Tables 3, 4, and 5). Chronic pain in the muscles, joints, and subcutaneous tissues was a common presenting symptom in patients with CFS. The potential contributing mechanisms may be oxidative and nitrosative stress, low-grade inflammation, and impaired heat shock protein production [35]. Another hypothesis concerning muscle fatigue is that it results from the overutilization of the lactate dehydrogenase pathway and slowed acid clearance after exercise [36]. The mainstream management of pain in CFS is similar to that for fibromyalgia. Pain can be treated with NSAIDs or acetaminophen. Pregabalin or gabapentin are helpful for neuropathic and fibromyalgia pain [37]; however, clinicians should be aware of the adverse effects of this treatment on cognitive dysfunction and weight gain. One systematic review indicated that cyclobenzaprine was more effective for back pain [38] but was associated with the side effects of drowsiness, dizziness, and dry mouth. Nonpharmacologic interventions for pain vary, and useful modalities include meditation, warm baths, massage, stretching, acupuncture, hydrotherapy, chiropractic, yoga, tai chi, and transcutaneous electrical nerve stimulation [14, 39].

According to the information released by NHIRD and clinical experiences, the supportive individual psychotherapy is performed by various professional members in psychiatric team under the psychiatrists’ guidance. The re-educative individual psychotherapy is mainly performed by psychotherapists and the intensive individual psychotherapy is administered by psychiatrists. Our results found the application of all psychotherapy was higher in the CFS cohort since those with psychiatric problems are mostly referred to psychotherapists for re-educative individual psychotherapy. However, the group psychotherapy is not a first choice for clinicians in Taiwan. In the age and sex subclassification analysis, psychotherapy was not prescribed significantly more frequently to young aged (below or equal to 34 y/o) patients. With regard to nonpharmaceutical options, cognitive behavioral therapy (CBT), a psychotherapy, has been prescribed to patients with CFS. CBT includes relaxation exercises, the development of coping mechanisms, and stress management, and it is an effective treatment for depression and anxiety and eating and panic disorders [40]. One randomized trial reported that CBT and graded exercise therapy (GET) were safe for CFS and effective at improving fatigue and functional impairment [41, 42]. A 16 week standard individual CBT has been shown to be beneficial in physical function and fatigue [43]. Furthermore, CBT is the most cost-effective treatment option for CFS [44]. Although CBT is often used with GET, the program should be discussed with patients to ensure their compliance.

Brainwave examination was also significantly more frequently prescribed in the CFS cohort (OR = 1.40; Table 2), regardless of whether the participant had depression, an anxiety disorder, or insomnia (Table 3). On the other hand, polysomnography (PSG), including brainwave examination (EEG), eye movements (EOG), muscle activity or skeletal muscle activation (EMG), and heart rhythm (ECG) records certain body functions during sleeping, Nonrestorative sleep is a key feature of CFS and is defined as the subjective experience that sleep has not been sufficiently refreshing or restorative [45, 46], resulting in increased daytime drowsiness, mental fatigue, and neurocognitive impairment [47]. Primary sleep disorders (PSDs), including primary insomnia, obstructive sleep apnea, periodic limb movement disorder, and narcolepsy, occur in approximately 18% of patients with CFS [48]. PSG is a key tool for detecting these disorders. Patients with more severe symptoms should be routinely screened for PSDs with appropriate questionnaires, a semistructured history interview, and PSG [49].

Some emerging management strategies for CFS have been proposed in recent years. The fact that drugs targeting immune responses or impaired autoregulation of blood flow was indicated to be effectual in CFS [50]. We previously discovered that the increased risk of CFS among patients with psoriasis was attenuated by immunomodulatory drugs [11]. In addition, a small placebo-controlled and open study mentioned that rituximab achieved sustained clinical responses in patients with CFS [51], and a clinical trial demonstrated that rintatolimod, a restricted toll-like receptor 3 agonist, achieved significant improvements in patients with CFS [52]. Furthermore, increased levels of several cytokines, including IL-1 and TNF-α, have been positively correlated with fatigue [53]. These findings provide insight into treating CFS through immune pathways. Another emerging treatment of CFS is dietary intervention, with one systemic review indicating that nicotinamide adenine dinucleotide hydride, coenzyme Q10, and probiotic supplements relieved CFS symptoms [54]. These potential mechanisms contribute by increasing adenosine triphosphate production and improving gut microbiota. Aripiprazole was reported to relieve the symptoms of CFS including fatigue and unrefreshing sleep effectively [55]. Biofeedback therapy has also demonstrated benefits in the treatment of CFS. Compared with GET, heart rate variability biofeedback therapy has improved quality of life in cases of mental health disorders, including depression, potentially through the enhancement of self-efficacy and self-control [56].

Our study has some limitations. First, the severity of CFS and efficacy of the treatment were not evaluated in the study because of limited information available in the NHIRD. Second, some nonpharmaceutical treatments, such as meditation and massage, were not included in our study because they were not included in the database. Third, patients’ personal information and family histories, such as symptoms, occupation, and laboratory data, were not available because of the anonymity of the NHIRD. Fourth, incorrect coding and diagnoses in the database may have resulted in bias in the data analysis; however, such errors may result in considerable penalties for physicians, and hence, they are unlikely. Moreover, data on 99.9% of Taiwan’s population are contained in the NHIRD, making the database a robust source of data, the reliability and validity of which have been reported previously [57]. Consequently, the diagnoses and codes should be reliable in our study.

Conclusion

In our nationwide population-based cohort study, the use of SSRIs, SARIs, SNRIs, TCAs, NDRI, BZD, muscle relaxants, analgesic drugs, psychotherapies and exercise therapies were prescribed significantly more frequently in the CFS cohort than in the control group. Previous studies have reported these treatments to be effective at relieving the symptoms of CFS and useful for managing related comorbidities.

Acknowledgements

We would like to extend acknowledgment to Dr. Jung-Nien Lai’s and Miss. Yu-Chi Yang's material support, and the listed institutes and Department of Medical Research at Mackay Memorial Hospital, and Mackay Medical College for funding support.

Author contributions

S-YT. had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: S-YT. Acquisition, analysis, or interpretation of data: K-HL, C-FK, and S-YT,. Drafting of the manuscript: All authors. Critical revision of the manuscript for important: S-YT. Intellectual content: S-YT; Statistical analysis: H-TY Obtained funding: S-YT, H-TY. Administrative, technical, or material supports: S-YT, and H-TY. Study supervision: S-YT. Submission: K-HL and S-YT. All authors read and approved the final manuscript.

Funding

This work was supported by the Taiwan Ministry of Health and Welfare Clinical Trial Center (MOHW109-TDU-B-212-114004), MOST Clinical Trial Consortium for Stroke (MOST 109-2321-B-039-002), China Medical University Hospital (DMR-109-231), Tseng-Lien Lin Foundation, Taichung, Taiwan, Mackay Medical College (1082A03), Department of Medical Research at Mackay Memorial Hospital (MMH-107-135; MMH-109-79; MMH-109-103).

Availability of data and materials

The data underlying this study is from the National Health Insurance Research database (NHIRD). Interested researchers can obtain the data through formal application to the Ministry of Health and Welfare, Taiwan.

Declarations

Ethics approval and consent to participate

The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national and institutional committees on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008. This study was approved by the Research Ethics Committee of the China Medical University Hospital (CMUH-104-REC2-115) and the Institutional Review Board of Mackay Memorial Hospital (16MMHIS074).

Consent for publication

The authors agree with the publication of this paper.

Competing interests

The authors declare that there is no conflict of interest regarding the publication of this paper.

Footnotes

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Kam-Hang Leong, Hei-Tung Yip and Chien-Feng Kuo are joint first authors and contributed equally to this paper

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

The data underlying this study is from the National Health Insurance Research database (NHIRD). Interested researchers can obtain the data through formal application to the Ministry of Health and Welfare, Taiwan.


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