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Bulletin of the World Health Organization logoLink to Bulletin of the World Health Organization
. 2018 Feb 5;96(4):243–255. doi: 10.2471/BLT.17.192658

Untreated depression and tuberculosis treatment outcomes, quality of life and disability, Ethiopia

Dépression non traitée et résultats du traitement contre la tuberculose, qualité de vie et handicap, Éthiopie

Resultados del tratamiento de la tuberculosis y la depresión sin tratar, calidad de vida y discapacidad, Etiopía

الاكتئاب غير المعالج ونتائج علاج السل، ونوعية الحياة والإعاقة في إثيوبيا

埃塞俄比亚未治疗抑郁症与肺结核治疗结果、生活质量和残疾程度的关系

Невылеченная депрессия и результаты лечения туберкулеза, качество жизни и инвалидизация, Эфиопия

Fentie Ambaw a,✉, Rosie Mayston b, Charlotte Hanlon c, Girmay Medhin c, Atalay Alem c
PMCID: PMC5872008  PMID: 29695881

Abstract

Objective

To investigate the association between comorbid depression and tuberculosis treatment outcomes, quality of life and disability in Ethiopia.

Methods

The study involved 648 consecutive adults treated for tuberculosis at 14 primary health-care facilities. All were assessed at treatment initiation (i.e. baseline) and after 2 and 6 months. We defined probable depression as a score of 10 or above on the nine-item Patient Health Questionnaire. Data on treatment default, failure and success and on death were obtained from tuberculosis registers. Quality of life was assessed using a visual analogue scale and we calculated disability scores using the World Health Organization’s Disability Assessment Scale. Using multivariate Poisson regression analysis, we estimated the association between probable depression at baseline and treatment outcomes and death.

Results

Untreated depression at baseline was independently associated with tuberculosis treatment default (adjusted risk ratio, aRR: 9.09; 95% confidence interval, CI: 6.72 to 12.30), death (aRR: 2.99; 95% CI: 1.54 to 5.78), greater disability (β: 0.83; 95% CI: 0.67 to 0.99) and poorer quality of life (β: −0.07; 95% CI: −0.07 to −0.06) at 6 months. Participants with probable depression had a lower mean quality-of-life score than those without (5.0 versus 6.0, respectively; P < 0.001) and a higher median disability score (22.0 versus 14.0, respectively; P < 0.001) at 6 months.

Conclusion

Untreated depression in people with tuberculosis was associated with worse treatment outcomes, poorer quality of life and greater disability. Health workers should be given the support needed to provide depression care for people with tuberculosis.

Introduction

Tuberculosis is the principal cause of death due to infectious disease worldwide;1 it accounts for 2.0% of the global disease burden, as measured in disability-adjusted life–years.2 In Ethiopia, tuberculosis is the fourth highest contributor to the disease burden.3 The World Health Organization’s (WHO’s) End-TB Strategy, launched in 2015, aims to achieve a treatment success rate of 90% by 2030 in all people with tuberculosis, including those with multidrug-resistant disease.1 People with tuberculosis often suffer from depression,4–6 which can reduce the likelihood of successful tuberculosis treatment,7 impair functioning8 and decrease quality of life.9 Systematic reviews have shown that depression is associated with poor medication adherence in people with human immunodeficiency virus (HIV) infections and acquired immune deficiency syndrome (AIDS).10 Moreover, in chronic noncommunicable diseases, depression has been observed to lead to poor treatment adherence and to lower immunity through neuroendocrine and behavioural mechanisms.11,12 These mechanism may also have a detrimental effect on responses to tuberculosis treatment.

Evidence on the impact of comorbid depression in tuberculosis is scarce.7 Although a few studies have assessed the association between depression and adherence to antituberculosis treatment, they were limited by small sample sizes of less than 70 patients. One study did analyse the relationship between depression and death or treatment discontinuation in people with tuberculosis,13 but we were unable to identify any study that disaggregated these outcomes. Other studies assessed disability14 and quality of life15 cross-sectionally or investigated changes from baseline in these variables after tuberculosis treatment.8 However, they did not evaluate the impact of comorbid depression, which is known to be an important cause of disability and poor quality of life in people with chronic disorders.11 Although global plans to end tuberculosis stress that both a patient-centred approach and social support are important for maximizing the treatment success rate, specific recommendations for people with comorbid depression is lacking.1

In addition, in low-income countries like Ethiopia, there are large gaps in treatment for mental health problems in general and for depression in particular.16 However, renewed efforts are being made to improve the detection and treatment of depression in primary health-care settings through WHO’s Mental Health Gap Action Programme (mhGAP).17 Greater understanding of the effect of untreated depression on the management of diseases important for public health, such as tuberculosis, is vital and would help ensure holistic care.

The aim of this study was to examine the impact of comorbid depression on treatment outcomes in people with tuberculosis in Ethiopia and on their health-related quality of life and level of disability.

Methods

Between December 2014 and July 2016, we conducted a prospective observational study of people who were newly diagnosed with tuberculosis at 14 primary health-care centres in south central (i.e. in Silti and Gurage zones) and northern (i.e. Bahir Dar zone) Ethiopia. Two centres were hospitals and 12 were health centres. Facilities were eligible for inclusion if they had staff trained in mhGAP, including the detection and treatment of depression. We recruited study participants within 1 month of starting antituberculosis treatment and who: (i) were aged 18 years or older; (ii) had no plans to move out of the study area; (iii) were well enough to be interviewed, as judged by the interviewer or prospective participant; (iv) had not been an inpatient for more than 5 days in the previous month; and (vi) had not been diagnosed with multidrug-resistant tuberculosis. Between 23 December 2014 and 4 February 2015, we consecutively invited people who fulfilled these criteria to participate in the study by health professionals running tuberculosis clinics at the study centres. Trained nurse research assistants provided those willing to participate with detailed information and obtained written informed consent or witnessed a thumb print at data collection. In Ethiopia, all people with newly diagnosed tuberculosis are treated using the directly observed treatment, short course (DOTS) approach: a combination of rifampicin, ethambutol, isoniazid and pyrazinamide is administered for the first 2 months and, subsequently, a combination of rifampicin and isoniazid is given for an additional 4 months.18

Study variables

The primary outcome variable was treatment default: a patient who defaulted was defined by the Ethiopian Federal Ministry of Health as one “who has been on treatment for at least four weeks and whose treatment was interrupted for eight or more consecutive weeks”.18 The timing of treatment default was taken to be midway between the last successful attempt to contact the person and the first unsuccessful attempt. Other treatment variables were treatment success, treatment failure and death due to any cause. Treatment was defined as successful if either the patient was cured (i.e. the sputum smear or culture became negative during, or in the last month of, treatment) or the treatment course was completed. Treatment was defined as having failed if the sputum smear or culture was positive 5 months or later after the start of treatment or a multidrug-resistant strain was present, irrespective of sputum smear or culture findings. Data on these variables were obtained from each centre’s tuberculosis register, which did not contain information after the time of referral on patients who were transferred to another area. The study protocol has been published elsewhere.19

The secondary outcome variables were quality of life and disability, which were assessed on three occasions over 6 months: (i) at baseline, at the start of the intensive treatment phase; (ii) at 2 months, after completion of the intensive treatment phase; and (iii) at 6 months, after completion of all tuberculosis treatment. Quality of life was assessed from responses to the question, “How would you rate your health-related quality of life?” and scored from zero for worst imaginable to 10 for best imaginable.20 Such single-item methods have been used successfully in population surveys, clinical settings and clinical interviews and found to be valid in indicating vulnerability to death due to all causes.21,22 No validated, tuberculosis-specific, quality-of-life instrument is available. Disability was assessed using the interviewer-administered version of the 12-item WHO Disability Assessment Schedule, version 2.0.23 This tool has been shown to be useful for assessing disability in primary care patients with depression and is able to capture changes over time.24,25 Moreover, it has been validated in Ethiopia and showed convergent validity with other predictors of impaired functioning in people with depression.26 At the three assessments, health professionals asked respondents if they were being treated for any mental illness, including depression.

Our exposure variable was probable depression which was identified using the nine-item version of the Patient Health Questionnaire and defined conservatively as a score of 10 or above.27,28 The nine-item version has been validated in two different treatment settings in Ethiopia.28,29 In the baseline assessment in our study, this version of the questionnaire was found to have construct validity and acceptable internal consistency, with an α of 0.81 and a mean inter-item correlation coefficient of 0.33.6 Participants who responded positively to the questionnaire item on suicidal ideation were referred for evaluation and treatment to health workers who had received training in mental health care as part of WHO’s mhGAP.30

We took into account a range of possible confounding variables such as age, sex, educational level, household income, marital status, religion, ethnicity and place of residence (i.e. urban versus rural). Data on these variables were obtained at baseline using a structured questionnaire. The duration of tuberculosis symptoms before diagnosis was self-reported by participants at baseline and information on the type of tuberculosis infection (i.e. pulmonary or extrapulmonary) was obtained from tuberculosis registers. The presence of any diagnosed comorbid chronic illnesses was also reported by participants themselves and whether or not they had an HIV infection, was recorded in tuberculosis registers. Use of substances, such as alcohol, tobacco and khat, was assessed using WHO’s Alcohol, Smoking and Substance Involvement Screening Test, version 3.1.31

Each participant’s perceived level of social support was assessed at baseline using the three-item Oslo-3 scale, which ranges from 3 to 14, with a high score indicating better perceived social support.32 This scale has previously been reported to work well in tuberculosis patients in Ethiopia.33 In addition, we assessed the stigma of tuberculosis at 2 months by adapting a 10-item tuberculosis stigma scale34 translated into Amharic;19 a high score indicated a high level of stigma. We also assessed participants’ perceptions about tuberculosis at 2 months: perceived tuberculosis severity was categorized as mild, moderate or severe; tuberculosis treatment was perceived as not helpful; somewhat helpful; or very helpful; and perceived barriers to tuberculosis treatment were identified from a yes or no answer to the question: “Are there barriers to taking your medications as prescribed?”

Data analysis

Study variables and the participants’ characteristics are presented using descriptive statistics. We estimated the association between probable depression at baseline and treatment default, treatment success and death using multivariate Poisson regression analysis with a robust variance estimator and present the results as risk ratios.35 The follow-up time was included as a weighting variable in the analysis of these outcomes. We did not perform multivariate analysis for treatment failure because there were only six cases. We assessed differences in quality-of-life and disability scores between participants with and without probable depression at baseline and at 6 months using the independent samples t test and the Mann–Whitney U test. To examine the change in health-related quality-of-life and disability scores between tuberculosis diagnosis and the end of antituberculosis treatment, we used a multilevel, mixed-effects, generalized linear model to fit data from the three measurement times (i.e. baseline, 2 months and 6 months), with the three measurement times nested within individuals and individuals nested within each of the 14 primary care centres. The analysis was performed using Stata version 13.1 (StataCorp LP., College Station, United States of America) and study findings are reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement.36

We calculated the study sample size using Stata version 12.0 for a power of 80%, a confidence level of 95% and an estimated prevalence of treatment default among tuberculosis patients without depression of 2.5%.37 In addition, the sample size had to be sufficient to detect a 5.0 percentage point increase in the prevalence of treatment default among people with comorbid depression when the ratio of nonexposure to exposure to depression was 2:1. With these parameters, the required sample size was 639, which was increased to 703 to include a 10% contingency for potential losses to follow up. The study was approved by the Institutional Review Board of the College of Health Sciences of Addis Ababa University (number 027/14/Psy).

Results

In total, 657 people were recruited. However, as 9 people were subsequently found to have been misdiagnosed with tuberculosis, the study analysis included data on only 648. Participants’ ages ranged from 18 to 85 years and 53.7% (348/648) were male (Table 1). The median time between starting tuberculosis treatment and the first assessment was 0 days (interquartile range, IQR: 2). Face-to-face follow up assessments were conducted with 91.4% of those with tuberculosis (592/648) at 2 months and 82.1% (532/648) at 6 months. The median time from the start of antituberculosis treatment to the second assessment was 56 days (IQR: 1) and the median time to the third assessment was 160 days (IQR: 3). Data on treatment outcomes at 6 months were available for 88.7% (575/648) of participants. Overall, 9.6% (62/648) were transferred out of study sites (Fig. 1). At baseline, 53.9% (349/648) scored 10 or higher on the nine-item Patient Health Questionnaire and were classified as having probable depression (Table 2) here was no significant difference at baseline between those who completed the study and those who were transferred out in the frequency of probable depression, level of disability or quality of life.

Table 1. Sociodemographic characteristics of participants, study of the association between depression and tuberculosis treatment outcomes, Ethiopia, 2014–2016.

Sociodemographic characteristic No. of participants (%)a n = 648
Sex
  Male 348 (53.7)
  Female 300 (46.3)
Age in years, mean (SD) 30 (16.0)
Marital status
  Single 210 (32.4)
  Married 358 (55.3)
  Widowed or divorced 80 (12.4)
Educational level
  No formal education 224 (34.6)
  Primary education 260 (40.1)
  Secondary education or higher 164 (25.3)
Occupation
  Unemployed 37 (5.7)
  Government employee 61 (9.4)
  Self-employed 133 (20.5)
  Farmer 172 (26.5)
  Student 39 (6.0)
  Homemaker 111 (17.1)
  Day labourer 44 (6.8)
  Other 51 (7.9)
Annual household income in Ethiopian birr, mean (SD)b 9 444 (13 200)
Religion
  Christian 429 (66.2)
  Muslim 219 (33.8)
Residence
  Urban 364 (56.2)
  Rural 284 (43.8)
Ethnicity
  Amhara 306 (47.2)
  Gurage 192 (29.6)
  Mareko 68 (10.5)
  Silte 65 (10.0)
  Other 17 (2.6)
Perceived social support
  Oslo-3 scale score, mean (SD)c 10 (4)
  Tuberculosis stigma scale score, mean (SD)d 26 (10)
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SD: standard deviation.

a All values in the table represent absolute numbers and percentages unless otherwise stated.

b In 2016, 1 Ethiopian birr = 22.5 United States dollars.

c The Oslo-3 scale score indicates the participant’s perceived level of social support (range: 3 to 14), with a high score indicating better perceived social support.32

d Tuberculosis stigma was assessed at 2 months in 592 participants using a 10-item scale (range: 10 to 50), on which a high score indicated a high level of stigma.

Fig. 1.

Fig. 1

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Flowchart, study of the effect of depression on tuberculosis treatment outcomes, Ethiopia, 2014–2016

Table 2. Illness and substance use, study of the effect of depression on tuberculosis treatment outcomes, Ethiopia, 2014–2016.

Variable No. of participants (%) n = 648
Probable depressiona at baseline 349 (53.9)
Suicidal ideation
  No 535 (82.6)
  Yes 113 (17.4)
Duration of tuberculosis symptoms before diagnosis, weeks
   < 2 40 (6.2)
  2–12 338 (52.2)
  13–52 209 (32.3)
   > 52 61 (9.4)
Type of tuberculosis
  Pulmonary 371 (57.3)
  Extrapulmonary 277 (42.8)
HIV status
  Negative 495 (76.4)
  Positive 74 (11.4)
  Unknown 79 (12.2)
Hypertension 1 (0.2)
Heart disease 3 (0.5)
Diabetes mellitus 5 (0.8)
Previous depression 0 (0.0)
Alcohol useb
  Low 562 (86.7)
  Moderate 74 (11.4)
  High 12 (1.9)
Tobacco useb
  Low 615 (94.9)
  Moderate 29 (4.5)
  High 4 (0.6)
Khat useb
  Low 544 (84.0)
  Moderate 93 (14.3)
  High 11 (1.7)
Perceived tuberculosis severityc
  Mild 62 (10.5)
  Moderate 85 (14.4)
  Severe 445 (75.2)
Perceived benefit of tuberculosis treatmentc
  Not helpful 2 (0.3)
  Somewhat helpful 23 (3.9)
  Very helpful 567 (95.8)
Perceived barriers to tuberculosis treatmentc
  No 458 (77.4)
  Yes 134 (22.6)
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HIV: human immunodeficiency virus.

a Probable depression was defined as a score ≥ 10 on the nine-item version of the Patient Health Questionnaire.27

b The use of substances, such as alcohol, tobacco and khat, was assessed at baseline using the World Health Organization’s Alcohol, Smoking and Substance Involvement Screening Test, version 3.1.31

c Participants’ perceptions of tuberculosis severity, the benefit of tuberculosis treatment and barriers to tuberculosis treatment were assessed at 2 months in 592 participants.

At 6 months, the treatment default rate was significantly higher among participants with probable depression at baseline than among those without: 3.9% (12/309) versus 0.8% (2/266), respectively (P < 0.05). Similarly, the proportion who had died was significantly higher among those with probable depression: 7.8% (24/309) versus 1.9% (5/266) in those without (P < 0.01). In addition, the treatment success rate was significantly lower in those with probable depression: 87.1% (269/309) versus 96.6% (257/266) in those without (P  < 0.001; Table 3). On multivariate analysis, treatment default by 6 months was independently associated with probable depression (adjusted risk ratio, aRR: 9.09; 95% confidence interval, CI: 6.72 to 12.30), as was death (aRR: 2.99; 95% CI: 1.54 to 5.78). However, there was no significant association with treatment success (aRR: 0.95; 95% CI: 0.91 to 1.00), though the upper confidence bound was borderline for significance (Table 4).

Table 3. Tuberculosis treatment outcomes, by presence of probable depression, Ethiopia, 2014–2016.

Indicator Participantsa
 P
With probable depression at baseline(n = 309) Without probable depression at baseline(n = 266)
Treatment outcome, no. (%)
  Treatment success 269 (87.1) 257 (96.6) < 0.001
  Treatment failure 4 (1.3) 2 (0.8) ND
  Treatment default 12 (3.9) 2 (0.8) < 0.05
  Death 24 (7.8) 5 (1.9) < 0.01
Quality-of-life score, mean  (SD)b,c
  At baseline before tuberculosis treatment 4.7 (2.7) 5.7 (2.4) < 0.001
  After 6 months of treatment 5.0 (2.4) 6.0 (2.2) < 0.001
Disability score, median(IQR)c,d
  At baseline before tuberculosis treatment 30 (16) 18 (8) < 0.001
  After 6 months of treatment 22 (19) 14 (4) < 0.001
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IQR: interquartile range; ND: not determined; SD: standard deviation.

a Treatment outcomes were known at 6 months for 575 of the 648 study participants: those who refused to be tested, were transferred to another area or whose diagnosis changed were excluded.

b Quality of life was assessed using the question, “How would you rate your health-related quality of life?” and scored from 0 (worst) to 10 (best).

c Quality-of-life and disability were assessed in 648 participants at baseline and in 532 at 6 months.

d Disability was assessed using the interviewer-administered version of the 12-item World Health Organization Disability Assessment Schedule, version 2.0 (score range: 0 to 60).23

Table 4. Factors associated with tuberculosis treatment outcomes, Ethiopia, 2014–2016.

Factor Outcome
Treatment success
 Treatment default
 Death
cRR (95% CI) aRR (95% CI) cRR (95% CI) aRR (95% CI) cRR (95% CI) aRR (95% CI)
Probable depressiona
  No Reference Reference Reference Reference Reference Reference
  Yes 0.96 (0.90 to 1.03) 0.95 (0.91 to 1.00) 5.53 (1.74 to 17.52) 9.09 (6.72 to 12.30) 4.42 (1.85 to 10.57) 2.99 (1.54 to 5.78)
Sex
  Male Reference Reference Reference Reference Reference Reference
  Female 1.02 (1.02 to 1.03) 1.01 (1.01 to 1.01) 0.45 (0.31 to 0.63) 0.37 (0.33 to 0.43) 0.90 (0.44 to 1.88) 1.16 (0.56 to 2.41)
Age, per year 1.00 (1.00 to 1.00) 1.00 (1.00 to 1.00) 1.03 (1.01 to 1.05) 1.05 (0.98 to 1.12) 1.05 (1.04 to 1.05) 1.04 (1.02 to 1.07)
Tuberculosis symptoms duration before diagnosis, weeks
  ≤ 12 Reference Reference Reference Reference Reference Reference
  > 12 0.99 (0.99 to 0.99) 0.99 (0.99 to 0.99) 0.57 (0.31 to 1.05) 0.44 (0.14 to 1.43) 1.51 (0.40 to 5.75) 1.57 (0.19 to 13.05)
Household income, per 13 200-birr increaseb 0.99 (0.98 to 1.00) 0.99 (0.99 to 1.00) 0.81 (0.47 to 1.39) 1.28 (0.77 to 2.11) 0.85 (0.79 to 0.91) 0.95 (0.64 to 1.39)
Residence
  Urban Reference Reference Reference Reference Reference Reference
  Rural 1.02 (1.01 to 1.04) 1.02 (1.02 to 1.03) 0.48 (0.29 to 0.81) 0.35 (0.25 to 0.49) 1.29 (1.13 to 1.48) 1.06 (0.96 to 1.17)
Type of tuberculosis
  Pulmonary Reference Reference 1.84 (1.49 to 2.27) 1.35 (0.76 to 2.40) 1.64 (1.15 to 2.34) 1.24 (0.39 to 3.89)
  Extrapulmonary 1.01 (0.99 to 1.04) 1.00 (1.00 to 1.00) Reference Reference Reference Reference
Educational level
  No formal education Reference Reference 1.76 (0.64 to 4.82) 1.48 (0.16 to 13.54) 2.11 (0.55 to 8.11) 0.53 (0.03 to 10.93)
  Primary education 1.0 (1.00 to 1.00) 1.00 (0.98 to 1.02) 2.18 (0.47 to 10.11) 2.05 (1.02 to 4.12) 2.02 (0.46 to 8.96) 0.95 (0.05 to 18.76)
  Secondary education or higher 0.99 (0.96 to 1.03) 1.02 (0.98 to 1.05) Reference Reference Reference Reference
Religion
  Christian Reference Reference Reference Reference Reference Reference
  Muslim 1.02 (1.00 to 1.04) 1.02 (0.97 to 1.06) 0.31 (0.25 to 0.38) 0.07 (0.05 to 0.11) 1.32 (0.55 to 3.16) 1.34 (0.93 to 1.92)
Marital status
  Single Reference Reference Reference Reference Reference Reference
  Married 1.03 (1.02 to 1.04) 1.06 (1.03 to 1.09) 0.84 (0.20 to 3.49) 0.61 (0.18 to 2.11) 3.72 (1.16 to 11.96) 1.76 (0.12 to 25.89)
  Widowed or divorced 1.03 (1.00 to 1.06) 1.07 (1.01 to 1.13) 2.47 (0.61 to 9.96) 1.71 (0.56 to 5.26) 4.94 (1.70 to 14.37) 1.73 (0.13 to 23.33)
HIV status
  Negative Reference Reference Reference Reference Reference Reference
  Positive 0.96 (0.95 to 0.98) 0.97 (0.96 to 0.97) NDc NDc 1.55 (0.23 to 10.27) 2.04 (0.23 to 17.80)
  Unknown 0.98 (0.94 to 1.02) 0.98 (0.93 to 1.03) 2.49 (0.80 to 7.77) 3.88 (0.79 to 18.99) 0.27 (0.21 to 0.34) 0.25 (0.19 to 0.32)
Alcohol used
  Low Reference Reference Reference Reference Reference Reference
  Moderate or high 0.95 (0.92 to 0.99) 0.96 (0.93 to 0.98) 1.84 (0.12 to 27.38) 0.48 (0.14 to 1.62) 0.78 (0.13 to 4.56) 0.90 (0.29 to 2.80)
Khat used
  Low Reference Reference Reference Reference Reference Reference
  Moderate or high 1.01 (0.98 to 1.04) 1.00 (0.98 to 1.02) 2.06 (0.70 to 6.07) 5.65 (2.18 to 14.63) 0.82 (2.61) 0.71 (0.09 to 5.68)
Perceived social support
  Oslo-3 scale, per 1-point increasee 1.00 (0.98 to 1.01) 1.00 (0.99 to 1.00) 0.81 (0.47 to 1.39) 0.91 (0.64 to 1.30) 1.10 (0.90 to 1.35) 1.13 (0.92 to 1.39)
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aRR: adjusted risk ratio; CI: confidence interval; cRR: crude risk ratio; HIV: human immunodeficiency virus; ND: not determined.

a Probable depression at baseline was defined as a score ≥ 10 on the nine-item version of the Patient Health Questionnaire.27

b The standard deviation household income was 13200 Ethiopian birr (Table 2) and 1 Ethiopian birr = 22.5 United States dollars in 2016.

c No participant with an HIV infection defaulted on treatment.

d The use of substances, such as alcohol and khat, was assessed using the World Health Organization’s Alcohol, Smoking and Substance Involvement Screening Test, version 3.1.31

e A high score on the Oslo-3 scale indicates better perceived social support.32

Probable depression at baseline was also associated with quality of life (Fig. 2) and disability (Fig. 3). The mean quality-of-life score at baseline was lower among those with probable depression than among those without (4.7 versus 5.7, respectively; P < 0.001) and the median disability score was higher (30.0 versus 18.0, respectively; P < 0.001). These differences remained significant at 6 months, when the mean quality-of-life score among those with and without probable depression was 5.0 and 6.0, respectively, (P < 0.001) and the median disability score was 22.0 and 14.0, respectively, (P < 0.001; Table 3). On multivariate analysis, quality of life at 6 months was significantly and negatively associated with probable depression (β = −0.07; 95% CI: −0.07 to −0.06) and disability was positively associated (β = 0.83; 95% CI: 0.67 to 0.99). There was no significant change over time in either mean quality-of-life score (β = −0.02; 95% CI: −0.13 to 0.09) or median disability score (β = −0.07; 95% CI: −0.33 to 0.22; Table 5). Data on factors other than depression that were associated with tuberculosis treatment outcomes are shown in Table 4 and data on factors associated with quality of life and disability are shown in Table 5.

Fig. 2.

Change in quality of life with tuberculosis treatment, by depression at baseline, Ethiopia, 2014–2016

Note: Quality of life was assessed on the basis of responses to the question, “How would you rate your health-related quality of life?” and scored from 0 (worst) to 10 (best).

Fig. 2

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Fig. 3.

Change in disability score with tuberculosis treatment, by depression at baseline, Ethiopia, 2014–2016

Note: Disability was assessed using the interviewer-administered version of the 12-item World Health Organization Disability Assessment Schedule, version 2.0 (score range: 0–60).23

Fig. 3

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Table 5. Factors associated with health-related quality of life and disability, study of the effect of depression on tuberculosis treatment outcomes, Ethiopia, 2014–2016.

Factor Quality-of-life scorea
 Disability scoreb
Crude β (95% CI)c Adjusted β (95% CI)c Crude β (95% CI)c Adjusted β (95% CI)c
PHQ-9 score,d per 1-point increase −0.08 (−0.11 to −0.05) −0.07 (−0.07 to −0.06) 0.92 (0.69 to 1.15) 0.83 (0.67 to 0.99)
Time after start of tuberculosis treatment 0.05 (−0.06 to 0.16) −0.02 (−0.13 to 0.09) −0.95 (−1.29 to −0.61) −0.07 (−0.33 to 0.22)
Sex
  Male Reference Reference Reference Reference
  Female −0.14 (−0.44 to 0.15) −0.04 (−0.18 to 0.11) 1.67 (0.48 to 2.86) 0.51 (0.09 to 0.93)
Age
  Below median Reference Reference Reference Reference
  Median and above −0.39 (−0.94 to 0.16) −0.10 (−0.47 to 0.28) 3.37 (−0.42 to 7.16) 1.26 (−0.78 to 3.29)
Tuberculosis symptoms duration before diagnosis, weeks
  < 2 1.02 (0.31 to 1.72) 0.42 (−0.27 to 1.11) −6.89 (−11.13 to −2.65) −2.37 (−4.08 to −0.66)
  2–12 0.22 (0.05 to 0.27) −0.18 (−0.76 to 0.40) −2.88 (−4.41 to −1.36) −0.77 (−1.98 to 0.45)
  13–52 0.01 (−0.24 to 0.27) −0.42 (−0.98 to 0.15) −1.79 (−2.82 to −0.75) −0.43 (−0.78 to −0.07)
  > 52 Reference Reference Reference Reference
Household income
  Below median Reference Reference Reference Reference
  Median and above 0.98 (0.75 to 1.21) 0.46 (0.45 to 0.47) −1.39 (−2.67 to −0.11) 0.07 (−0.04 to 0.18)
Residence
  Urban Reference Reference Reference Reference
  Rural −0.47 (−1.00 to 0.07) −0.35 (−0.47 to −0.22) 1.63 (1.10 to 2.15) −0.01 (−1.20 to 1.19)
Type of tuberculosis
  Pulmonary Reference Reference Reference Reference
  Extrapulmonary 0.14 (−0.25 to 0.53) −0.05 (−0.13 to 0.03) −1.76 (−2.41 to −1.11) −0.92 (−1.38 to −0.46)
Educational level
  No formal education −1.00 (−1.23 to −0.77) −0.22 (−0.62 to 0.18) 5.66 (2.43 to 8.89) 1.47 (0.55 to 2.39)
  Primary education −0.51 (−0.55 to −0.47) −0.12 (−0.24 to 0.00) 1.45 (−0.28 to 3.18) −0.47 (−1.14 to 0.20)
  Secondary education or higher Reference Reference Reference Reference
Perceived tuberculosis severity
  Mild Reference Reference Reference Reference
  Moderate −0.27 (−0.52 to −0.03) −0.38 (−0.43 to −0.32) −0.26 (−1.37 to 0.85) 0.22 (−0.80 to 1.23)
  Severe −0.74 (−1.10 to −0.37) −0.45 (−0.58 to −0.33) 4.39 (3.23 to 5.56) 2.54 (1.37 to 3.71)
Perceived barriers to tuberculosis treatment
  No Reference Reference Reference Reference
  Yes −0.41 (−1.17 to 0.35) −0.12 (−0.68 to 0.45) 3.24 (2.18 to 4.31) 1.44 (−0.05 to 2.93)
Religion
  Christian Reference Reference Reference Reference
  Muslim 0.09 (−0.06 to 0.24) 0.11 (−0.12 to 0.34) 1.48 (0.09 to 2.87) 1.78 (1.66 to 1.90)
Marital status
  Single Reference Reference Reference Reference
  Married 0.06 (−0.94 to 1.07) 0.40 (0.03 to 0.77) 2.20 (−3.02 to 7.41) −0.51 (−1.67 to 0.64)
  Widowed or divorced −0.99 (−1.9 to −0.77) −0.33 (−0.81 to −0.14) 5.42 (−1.56 to 12.39) 0.75 (−2.14 to 3.64)
HIV status
  Negative Reference Reference Reference Reference
  Positive −0.36 (−0.64 to −0.08) −0.06 (−0.11 to −0.00) 1.82 (−0.54 to 4.17) 0.63 (−0.99 to 2.25)
  Unknown 0.26 (0.23 to 0.28) 0.23 (0.09 to 0.38) −0.63 (−1.40 to 0.30) −0.13 (−0.29 to 0.04)
Alcohol usee
  Low Reference Reference Reference Reference
  Moderate or high −0.09 (−0.46 to 0.29) 0.13 (−0.55 to 0.82) 0.68 (−0.28 to 1.64) 0.96 (−0.06 to 1.97)
Khat usee
  Low Reference Reference Reference Reference
  Moderate or high −0.13 (−0.36 to 0.11) −0.24 (−0.44 to −0.04) −0.80 (−0.89 to −0.71) −0.98 (−1.31 to −0.65)
Perceived social support
  Oslo-3 scale score, per 1-point increasef 0.27 (0.20 to 0.34) 0.20 (0.14 to 0.25) −0.39 (−0.82 to 0.04) 0.05 (−0.36 to 0.47)
  Tuberculosis stigma scale score, per 1-point increaseg −0.09 (−0.15 to −0.03) −0.03(−0.08 to −0.01) 0.45 (0.39 to 0.51) 0.16 (0.15 to 0.16)
Open in a new tab

CI: confidence interval; HIV: human immunodeficiency virus; PHQ-9: nine-item version of the Patient Health Questionnaire.

a Quality of life was assessed on the basis of responses to the question, “How would you rate your health-related quality of life?” and scored from 0 (worst) to 10 (best).

b Disability was assessed using the interviewer-administered version of the 12-item World Health Organization Disability Assessment Schedule, version 2.0 (score range: 0 to 60).23

c The β values were derived using a multilevel, mixed-effects, generalized linear model.

d Probable depression at baseline was defined as a score ≥ 10 on PHQ-9, on which scores ranged from 0 to 27.27

e The use of substances, such as alcohol and khat, was assessed using the World Health Organization’s Alcohol, Smoking and Substance Involvement Screening Test, version 3.1.31

f A high score on the Oslo-3 scale indicates better perceived social support.32

g A high score indicates greater stigma.

Discussion

Our study provides evidence that people with tuberculosis in Ethiopia who had probable depression at the start of treatment were significantly more likely to default on treatment or die. Moreover, their chance of successful treatment was lower. Previous studies have also reported that depression compromises adherence to essential scheduled health care.11 With tuberculosis, treatment default leads to transmission of the infection to others, thereby raising the odds of further defaults,38 and increases the risk of multidrug-resistant disease.39

In agreement with our observations, systematic reviews and large population-based studies in both high- and low-income settings have found that mortality is increased in people with depression and that the association is maintained across patient groups.40–43 However, depression is a more serious concern for people with tuberculosis in Ethiopia because comorbid depression has been found in the majority.6 The mechanism by which depression increases mortality is likely to be complex. Although 113 of our 648 study participants reported suicidal ideation, we were not able to confirm its contribution to the mortality observed. One systematic review found that suicide contributed to less than 1.0% of deaths in medical samples like ours.41 Moreover, in our study area, the commonest cause of death in people with severe mental illness is infectious disease.44 In people with tuberculosis, depression may increase mortality through decreased self-care, including failure to take medications as prescribed,11 and through disability leading to poverty and substandard living conditions. One possible biological mechanism is depression-associated immune suppression.45

We also found that probable depression in people with tuberculosis was associated with poorer quality of life and greater disability, both at the start and after completion of antituberculosis treatment. In previous studies, neither quality of life nor the degree of disability returned to levels normal for the population by the end of tuberculosis treatment.8,46 Possible explanations are underlying depression, the quality of tuberculosis care falling short of international standards and the socioeconomic consequences of the illness and its associated stigma.47,48 One implication of these findings is that evaluating disability only during episodes of tuberculosis is likely to underestimate the disease burden as continuing disability after clinically successful treatment would be ignored.49

The treatment default rate we observed was markedly lower in females, rural residents and people living with HIV. Treatment adherence may have been stronger in people with an HIV infection, because of the counselling and additional support given to them in the Ethiopian health-care system, particularly in rural communities.50 Treatment default was also associated with higher khat use, substance use has previously been found to reduce the tuberculosis treatment success rate.51 In Ethiopia, the implementation of integrated care for people with mental, neurological and substance use disorders does not include khat use disorder as a target condition, because little is known about its adverse consequences and, because practical interventions are lacking. The level of disability was higher in females, in participants who perceived their episode of tuberculosis as severe, in those with pulmonary rather extrapulmonary tuberculosis and in those with a high level of stigma, indicating that both physical and psychosocial factors may contribute to the development of disability.52

Although we found that comorbid depressive symptoms in people with tuberculosis are often associated with poorer outcomes, even with successful treatment, generally health-care providers in Ethiopia do not assess depression in these people or provide evidence-based treatment. Consequently, unnoticed comorbid depressive symptoms may hamper efforts to end tuberculosis. National tuberculosis treatment guidelines may need to address depressive symptoms directly and health professionals should be trained to detect and treat depression in the context of the disease.

Our study has several of limitations. In our sample size calculation, we assumed that the tuberculosis treatment default rate in people without depression was 2.5%, which was based on a national report. We found a rate of 0.8%. However, we were still able to obtain estimates even with this sample size and do not believe it critically affected our findings. Second, in the low-income setting of our study, participants could have had undiagnosed, comorbid physical illnesses. Third, as we did not know whether or not participants were treated for depression outside the study centres, we may have overestimated the frequency of untreated depression. Nonetheless, as few people with depression receive treatment in Ethiopia, it is unlikely that misclassification of untreated depression seriously affected our results. Fourth, poverty may not have been fully captured by our sociodemographic variables and may have been a confounding factor. Fifth, as quality of life was assessed using a single question, no detailed information on different dimensions of quality of life was available. Sixth, we had no information on whether participants transferred out of the study area differed significantly from others in treatment outcomes or final quality-of-life or disability scores. However, there were no differences at baseline. Finally, our conclusions cannot be extended to tuberculosis patients who are hospitalized, are being retreated, or have multidrug-resistant disease.

Nevertheless, consecutive patients were recruited and our study sample was reasonably representative, because several sites were included, all eligible people were invited to participate and data were collected over a long enough period to take seasonal variations into account.53 Use of the DOTS approach to tuberculosis treatment in Ethiopia means that our findings are generalizable to settings in low- and middle-income countries using a similar approach.

In conclusion, untreated depression appears to be a strong risk factor for treatment default and death in people with newly diagnosed tuberculosis and is associated with poor health-related quality of life and greater disability, despite successful tuberculosis treatment. Consequently, health-care workers should be given the support needed to provide depression care for people with tuberculosis.

Acknowledgements

We thank the study participants, research assistants, and health-care professionals and officials at participating health-care centres.

Funding:

The study was mainly funded by the European Union’s Seventh Framework Programme (FP7/2007–2013), under Emerald grant agreement number 305968, and partially funded by the Psychiatry Research Trust.

Competing interests:

None declared.

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