6. The longer regimens

The design of longer regimens (18–20 months) is founded on grouping of medicines recommended for use in longer regimens based on the drug-resistance profile (Table 6.1).

In ideal conditions, only a small proportion of MDR/RR-TB patients should opt for longer regimens, because this indication is mainly for those who cannot benefit from either BPaLM/BpaL or the 9-month all-oral regimen. Reasons for not using the shorter regimens may be related to the age of the patients, additional resistance (including fluoroquinolone resistance and other Group A medicines; i.e. XDR-TB), intolerance to key medicines used in shorter regimens, severity of disease, pregnancy, certain types of extrapulmonary TB or other complications needing an individualized approach.

Under many of these circumstances, only less potent and more toxic drugs are left to be used for treatment and lengthy regimens are therefore needed to cure without relapse. Longer regimens, especially if clinical conditions are complex (e.g. advanced disease with higher burden of bacilli and severe disease affecting critical organs) are usually associated with higher likelihood of toxicity, owing to factors such as longer drug exposure, higher intolerance, adverse effects and greater potential for drug–drug interactions in critically ill patients.

All these conditions that may lead to less patient-friendly regimens with higher pill burden and toxicity can increase the likelihood of unfavourable treatment outcomes such as treatment failure, loss to follow-up and death. All DR-TB patients need a patient-centred approach with treatment adherence support and aDSM, but in longer regimens these activities become more crucial. Patients will need support to overcome the hardships associated with TB and its treatment, including daily adherence challenges, adverse drug reactions, indirect costs and stigma.


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