People treated for active TB remain at high risk for recurrent TB (relapse or reinfection), particularly in the first 2 years post-treatment.28,29 TB recurrence is associated with worse morbidity, mortality and acquired drug resistance, along with the renewed potential for transmission of infection to contacts. In a recent systematic review examining TB recurrence in low-incidence regions, the pooled recurrence rate was 1.47 (95% CI: 0.87-2.46) per 100 person years, with 83% of people with recurrence experiencing relapse.59 This TB incidence rate exceeds the TB incidence rate in many people receiving TB screening and treatment for latent TB in Canada (see Chapter 6: Tuberculosis Preventive Treatment in Adults). People at high risk of TB recurrence may include people with extensive or disseminated disease, cavitary and smear or culture positive disease, drug-resistant disease, people with immune suppressing co-morbidities, people with a history of treatment interruptions, non-adherence or an atypical treatment regimen.
Understanding the timing of recurrence is important to inform follow-up. A review of 15 tuberculosis treatment trials from 1970-1983 involving RMP and that contained regimens for drug-susceptible TB found that 78% of recurrences occurred within six months of therapy and 91% within 12 months.60 Some programs perform routine post-treatment surveillance to ensure timely diagnosis of TB recurrence. Routine monitoring may include regular review of symptoms or chest x-rays in the 12-24 months post-TB treatment. A recent post-hoc analysis of systematic review data demonstrated a non-significant increase in the diagnosis of recurrent TB in people with active follow-up with chest x-rays compared with passive follow-up (L. Otero, personal communication).59
Recommendation
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We conditionally recommend that people with a high risk for TB recurrence post-treatment should be monitored for signs/symptoms of TB recurrence during the first 12-24 months post-therapy. This may include use of symptom review and radiological or microbiological testing (poor evidence).
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