The World Health Organization's quality of life scale - short form (WHOQOL-BREF) is a 26-item version of the WHOQOL-100. It was developed to be a cross-culturally applicable tool for the subjective evaluation of health-related quality of life and was designed in diverse cultural settings, with field trials including Nigeria. The psychometric properties of WHOQOL-BREF have been described in more than 11,000 adults from 23 countries.120 Analyses of internal consistency, reliability, item–total correlations, discriminant validity and construct validity have indicated that the WHOQOL-BREF has good to excellent psychometric properties of reliability and validity.120 It measures four broad domains namely physical health, psychological (mental) health, social relationship and the environment. The tool has 26 items
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which are scored on a Likert scale of 1 - 5. Scores are scaled in a positive direction, with higher scores denoting a more optimistic response and a higher quality of life. Negatively phrased questions are reverse-scored, thus transforming them into positively-scaled questions. It has been translated into over 20 languages, including Yoruba.121,122
The physical domain (domain 1) incorporates the following facets: activities of daily living, dependence on medicinal substances and medical aid, energy and fatigue, mobility, pain and discomfort, sleep and rest, work capacity. It reflects the capacity of the patient to carry out everyday activities. The psychological domain (domain 2) assesses bodily image and appearance, negative feelings, positive feelings, self-esteem, spirituality/religious/personal beliefs, thinking, learning, memory and concentration. This domain takes into account facets of the individual's mood and emotional wellbeing. The social relationships domain (domain 3) assesses personal relationships, social support and sexual activities. Summarily, it describes interaction with other people at home, work, and within the larger society. Environment (domain 4) relates to financial resources, freedom/physical safety/security, accessibility and quality of health and social care, home environment, opportunity for acquiring new information and skills, participation in and opportunities for recreation and leisure activities, physical environment (pollution/noise/traffic/climate) and transport. The four domain scores denote an individual’s perception of quality of life in each particular domain. Higher scores of 4 and 5 indicated a higher quality of life while lower scores below 3 indicated a low quality of life.26,123 In Nigeria, WHOQOL-BREF has been applied extensively on HIV patients, the elderly, stroke survivors, people with diabetes mellitus, schizophrenia, depression and asthma; and has been found to be a valid and reliable tool.67,124–130 The validity of a Yoruba-translated version when applied on bilingual stroke survivors correlated significantly with those on its English version (r = 0.695-0.859; p < 0.001).121 Although normative data for Nigerian adults are not widely available, a few studies in Nigeria have provided insight into quality of life of apparently
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healthy Nigerian adults using the WHOQOL-BREF, such as a community-based study in South-western Nigeria.24 The study measured HRQOL of 527 adults in a semi-urban area of Ogun State and dichotomized the aggregated scores from the WHOQOL-BREF. Scores less than 78 (which corresponds to an average response of 3 or below on each item) were categorized as poor QOL e scores equal to and above 78 were categorised as good QOL. The majority of the community dwellers had good quality of life in the study. Up to 78.7% of respondents reported their overall quality of life as good based on a single scaled question while 81.6% had good QOL by scoring equal to or above 78, using the aggregate scores from the administration of the WHOQOL-BREF.24 However the breakdown of scores in each domain was not provided.
a. WHOQOL-BREF Assessments in patients with tuberculosis
Studies have been carried out to assess HRQOL in patients with tuberculosis using the WOHQOL-BREF. Most have been cross-sectional in design, although a few followed up patients prospectively from the time of diagnosis until treatment was completed.39,60,71,131,132 A few researchers have also gone further, examining the relationship between quality of life and chronic sequelae of TB in previously treated patients. Some studies have also compared HRQOL between latent and active cases.37 These studies which include both developing and developed countries, have shown that subjects with active TB consistently reported poorer HRQOL than subjects treated for latent tuberculosis infection (LTBI) and apparently well controls, although scores tend to improve over the course of treatment.40,60,71
In Nigeria, studies on HRQOL in TB patients were conducted in Ilorin and Lagos. They were both cross-sectional in design.42,71 The study in Ilorin evaluated HRQOL in 154 PTB patients in a teaching hospital. The researchers found mean scores but also categorized the HRQOL scores into good, fair and poor. The HRQOL of the patients was found to be impaired in all the
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health domains despite receiving at least two months of treatment with anti-tuberculosis drugs.
About 36% of the respondents reported health satisfaction as good as opposed to only 13.6%
reporting good HRQOL in the social domain. The study in Lagos was also conducted in a teaching hospital. Two hundred and sixty patients with PTB were evaluated for health-related quality of life. In this study, the HRQOL scores were dichotomised in accordance with the WHOQOL-BREF guideline. A low quality of life score was taken as a raw score of 21 or less in domain 1; 18 or less in domain 2; 9 or less in domain 3; and 24 or less in domain 4 (translating to a transformed score of 50 or less in all the domains). The highest mean transformed quality of life score was recorded in social relationship domain (70.80±18.12) while the lowest was in the environmental domain (66.33± 15.20). The mean transformed quality of life scores in the other domains of health included 67.40±22.20 in the physical and 66.75±16.60 in the psychological domains respectively.71 In these two studies, there were no comparisons of HRQOL with healthy controls. The studies did not elaborate on the different treatment categories of TB patient, specifically new versus re-treatment patients.
A study in India which was longitudinal in design, quantified impairment in HRQOL at the time of diagnosis using the WHOQOL-BREF, but also assessed patients during treatment as well. The study assessed the utility of this assessment as a measure of outcome under programme conditions. This study had a very large sample size of over a thousand patients and 68% were sputum-positive. All four domain scores of the WHOQOL-BREF showed significant positive correlation with the two global questions - overall rating of quality of life and overall satisfaction with health. Overall mean scores in the four domains ranged between 45.3 ± 17.4 in the physical domain, and 59.0 ± 17.3 in the social relationships domain. All domain scores improved significantly at the end of the intensive phase except for patients with persistent sputum positivity. All domain scores at the third assessment were significantly better than the corresponding scores at the second or first assessment.60 The key limitation of this study was
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that there was no control group for comparison, and normative data were not available for the Indian population.
b. Comparison of HRQOL in TB patients and controls using WHOQOL-BREF
Another Indian study assessed the HRQOL of TB patients using the Hindi version of the WHOQOL-BREF.133 About 90 TB patients being treated at a DOTS centre were matched with controls from the general population. The TB patients had significantly lower mean scores than the controls for overall HRQOL and its domains, with the physical and the psychological domains being worst affected. The patients scored highest in the social domain (14.35 ± 2.50, out of a maximum possible score of 20. Females had a lower mean score (11.67 ± 1.26) than the males (11.85 ± 1.66) for overall HRQOL and the social domain (male vs. female: 14.59 ± 2.35 vs. 14.38 ± 2.49).133
A study in Taiwan evaluated the psychometric properties of the Taiwanese version of the WHOQOL-BREF questionnaire, comparing 140 PTB patients and 130 healthy controls. The Taiwan version consists of two region-specific/national items in addition to the normal 24 domain-specific items. Although the results of the univariate analyses indicated that healthy controls had higher scores than TB patients in the four WHOQOL-BREF domains, the mean difference in the scores between the two groups in social relationship domain were not statistically significant.134
Some studies compared patients with TB with other groups that had a co-morbidity.41,134 A study conducted in northern India assessed the impact of MDR-TB on HRQOL by comparing HRQOL in 60 individuals with MDR-TB and 60 with PTB (drug-sensitive). The study findings showed that HRQOL of MDR-TB patients was worse than those with PTB. The psychological and environmental domains (MDR-TB vs. PTB 17.46 vs. 15.23 and 22.00 vs 18.91 respectively) were more affected compared to physical and social domains (MDR-TB vs. PTB
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19.03 vs 20.05 and 7.88 vs 9.61).41 Another study conducted in Saudi Arabia also compared HRQOL in MDR-TB and drug-sensitive PTB patients. There were statistically significant differences between DR-TB and non-DR-TB in overall HRQOL, psychological, and environmental domains (P = .000, .029, .001, .005 respectively). Physical health scores were similar in both groups (MDR-TB vs. PTB 55.26 vs 54.65, p=0.90). The main limitation of that study was a lack of information on HIV status which could be an important confounder in these groups of patients.135 A review of longitudinal HRQOL measures in subjects treated for TB that were evaluated at the beginning of treatment, after the initial phase and at near the end of treatment, showed that the greatest improvement in HRQOL occurred during the first 2 -3 months of treatment.37,40,60 However, some studies also showed that although HRQOL scores improved over the course of treatment, the scores at the end of treatment were lower than values for apparently well individuals without TB.60,136