A self-rated health score predicts severe disease and high mortality in patients with pulmonary TB

BACKGROUND: Health-related quality of life (HRQoL) in patients with pulmonary TB may be predictive of disease outcome; however, HRQoL instruments are often complicated and unsuitable for use in low-resource settings. A single-item self-rated health (SRH) score may represent a simpler alternative which could be used in clinical decision-making. AIMS: To evaluate internal and external validity of SRH and its correlation with TBscore/TBscoreII in a low resource setting. METHODS: We used data from our ongoing prospective TB cohort study in Guinea-Bissau. Cohen's d was used to assess internal validity, and receiver-operating characteristics and mortality statistics to assess external validity. Correlation between SRH and TBscore/TBscoreII was estimated using linear regression. RESULTS: SRH showed satisfactory internal validity and ability to discriminate between fatal cases at high and low scores, although not at middling scores. SRH and TBscore/TBscoreII correlated well at each examination but changes in scores did not, which may be due to ceiling/floor effects and a lag between disease severity and HRQoL. CONCLUSION: SRH shows potential as a quick and simple method to identify patients in need of intensified follow-up during treatment provision. More research is needed to assess its generalisability beyond our setting and to develop models for clinical use of SRH.