Health-related quality of life and its association with medication adherence in active pulmonary tuberculosis in South Africa - an integrated patient-centered outcomes approach

Introduction: Tuberculosis (TB) is a leading cause of morbidity and mortality in South Africa. Whilst clinical parameters are important objective outcomes in TB, they are often not directly correlated with the subjective well-being of the patient which can be assessed using patient- reported outcome (PRO) measures. Health-related quality of life (HRQOL) is a specific PRO of multi-dimensional nature, which includes physical, mental and social health domains. Furthermore, HRQOL may be associated with medication adherence. The thesis evaluates HRQOL and its association with medication adherence in TB in South Africa.
Methods: A systematic review on HRQOL and adherence in TB was conducted. Based on the findings, a conceptual framework for HRQOL in TB was developed as a basis for identifying PRO measures, and to generate an endpoint model. The two generic measures SF-12 and EQ-5D-5L, the respiratory-specific measure St. George´s Respiratory Questionnaire (SGRQ), the condition-specific measure Hospital Anxiety and Depression Scale (HADS) for HRQOL and well-being assessment and the Morisky Medication Adherence Scale (MMAS) for adherence assessment were finally selected. All these measures were applied in an observational, longitudinal, multicentre study at five data collection time points during the six- month standard TB treatment. Eligible patients were older than 18 years, new TB cases and were diagnosed without HIV co-infection. Change over time in the Physical Component Score (PCS-12) of SF-12 was defined as primary endpoint. Sample size estimation based thereupon has led to a recruitment target of 96 patients. Statistical analysis included significance testing, correlations, univariable and multivariable analysis, and repeated measures ANOVA. Results: A total of 131 patients participated in the study. Whilst HRQOL was impaired in all physical, mental and psycho-social health domains at the start of standard TB treatment, it improved significantly, and in a clinically meaningful manner, during the course of treatment. The greatest improvement in average mean score from baseline to six-month treatment (+95%) was observed in mental health. Younger patients with higher education and in employment reported a better HRQOL. Adherence mean scores stayed constant with participants attaining a medium average level throughout the treatment course. Associations between HRQOL and adherence were mainly weak, and included a positive relationship with improvements in anxiety and depression, pain and discomfort, and psycho-social health aspects after six months of treatment.
Discussion: This was the first longitudinal study in South Africa which evaluated HRQOL and its association with medication adherence in TB following a patient-centred and integrative approach. The study demonstrated the need for an integrative understanding of TB with HRQOL as one of the core elements to inform gaps in current TB management. In addition to an adequate drug treatment, the management of TB should also include services that focus
on mental and psycho-social needs of the patient.
Conclusion: An understanding about patient-reported HRQOL in TB treatment should support the identification of sustainable health innovations in TB, help determining the value of new products, and support decision making with regard to health policy and pricing. In addition, an integrative patient-centred approach can contribute towards supporting the Sustainability Development Goal 3 target and the End TB strategy of the World Health Organization.