BCG is protective against death in male but not female patients with pulmonary tuberculosis in Guinea-Bissau

Background Growing evidence supports the existence of a sex difference in immunity to tuberculosis (TB). This is most often to the detriment of males. This study aimed to assess the association between scar size from bacillus Calmette-Guerin (BCG) and mortality risk stratified by sex. Methods Kaplan-Meier survivor functions and Cox proportional hazard models were used to assess mortality risk by sex and scar size. Groups were further compared by clinical and epidemiological characteristics. Results Between 2003 and 2019, 2944 eligible patients were identified, of whom 1003 were included in the final analysis. Males with BCG scars, particularly large scars, were less likely to die within 1 y of diagnosis than males with no scar (adjusted hazard ratio 0.36 [95% confidence interval 0.15 to 0.88]). In contrast, females with small scars trended towards higher mortality than females with no scars or females with large scars. Conclusions BCG protects against death in male but not female patients with TB. More research is needed to determine the mechanisms underpinning these sex differences and whether they are generalizable beyond this setting.