Multimorbidity prevalence and chronic disease patterns among tuberculosis survivors in a high-income setting.

OBJECTIVES
Multimorbidity is the presence of two or more chronic health conditions. Tuberculosis (TB) survivors are known to have higher prevalence of multimorbidity, although prevalence estimates from high-income low-TB incidence jurisdictions are not available and potential differences in the patterns of chronic disease among TB survivors with multimorbidity are poorly understood. In this study, we aimed to (1) compare the prevalence of multimorbidity among TB survivors with matched non-TB controls in a high-income setting; (2) assess the robustness of aim 1 analyses to different modelling strategies, unmeasured confounding, and misclassification bias; and (3) among people with multimorbidity, elucidate chronic disease patterns specific to TB survivors.


METHODS
A population-based cohort study of people immigrating to British Columbia, Canada, 1985-2015, using health administrative data. Participants were divided into two groups: people diagnosed with TB (TB survivors) and people not diagnosed with TB (non-TB controls) in British Columbia. Coarsened exact matching (CEM) balanced demographic, immigration, and socioeconomic covariates between TB survivors and matched non-TB controls. Our primary outcome was multimorbidity, defined as ≥2 chronic diseases from the Elixhauser comorbidity index.


RESULTS
In the CEM-matched sample (n=1962 TB survivors; n=1962 non-TB controls), we estimated that 21.2% of TB survivors (n=416), compared with 12% of non-TB controls (n=236), had multimorbidity. In our primary analysis, we found a double-adjusted prevalence ratio of 1.74 (95% CI: 1.49-2.05) between TB survivors and matched non-TB controls for multimorbidity. Among people with multimorbidity, differences were observed in chronic disease frequencies between TB survivors and matched controls.


CONCLUSION
TB survivors had a 74% higher prevalence of multimorbidity compared with CEM-matched non-TB controls. TB-specific multimorbidity patterns were observed through differences in chronic disease frequencies between the matched samples. These findings suggest a need for TB-specific multimorbidity interventions in high-income settings such as Canada. We suggest TB survivorship as a framework for developing person-centred interventions for multimorbidity among TB survivors.