Benefits of combined preventive therapy with co-trimoxazole and isoniazid in adults living with HIV: time to consider a fixed-dose, single tablet coformulation

Summary Antiretroviral therapy (ART) is the main intervention needed to reduce morbidity and mortality and to prevent tuberculosis in adults living with HIV. However, in most resource-limited countries, especially in sub-Saharan Africa, ART is started too late to have an effect with substantial early morbidity and mortality, and in high tuberculosis burden settings ART does not reduce the tuberculosis risk to that reported in individuals not infected with HIV. Co-trimoxazole preventive therapy started before or with ART, irrespective of CD4 cell count, reduces morbidity and mortality with benefits that continue indefinitely. Isoniazid preventive therapy as an adjunct to ART prevents tuberculosis in high-exposure settings, with long-term treatment likely to be needed to sustain this benefit. Unfortunately, both preventive therapies are underused in low-income and high-burden settings. ART development has benefited from patient-centred simplification with several effective regimens now available as a one per day pill. We argue that co-trimoxazole and isoniazid should also be combined into a single fixed-dose pill, along with pyridoxine (vitamin B6), that would be taken once per day to help with individual uptake and national scale-up of therapies.