Isoniazid mono-resistant tuberculosis: Time to take it seriously

Area of Science:

• Tuberculosis Research
• Infectious Diseases Epidemiology
• Public Health Interventions

Background:

• Rifampicin resistance testing is prioritized in drug-resistant tuberculosis (DRTB) diagnosis, potentially overlooking isoniazid resistance.
• Failure to detect isoniazid resistance can lead to inappropriate treatment, poor outcomes, and the emergence of multidrug-resistant (MDR) TB.
• Isoniazid mono-resistance requires specific diagnostic attention and tailored treatment strategies.

Purpose of the Study:

• To evaluate the prevalence of isoniazid mono-resistance among DRTB patients in India.
• To assess treatment outcomes for isoniazid mono-resistance under the Revised National Tuberculosis Control Programme (RNTCP).
• To identify patient and disease-related factors associated with treatment success or failure.

Main Methods:

• Retrospective analysis of medical records of 52 isoniazid mono-resistant TB patients treated between January 1 and December 31, 2017.
• Collection of data on patient demographics, medical history, mutation types, and treatment outcomes.
• Statistical analysis to determine associations between various factors and treatment outcomes.

Main Results:

• Isoniazid mono-resistance accounted for 50.5% of DRTB cases studied.
• Cure rates were significantly higher in females (93.3%) compared to males (58.8%) (p=0.019).
• Younger patients (<30 years) showed better cure rates (84%) than older patients (≥30 years) (54.2%) (p=0.032).
• Primary isoniazid mono-resistance was associated with better cure rates than previous loss to follow-up (p=0.04).
• Factors like mutation type, weight, protein levels, smoking, DM, anemia, ADRs, and intensive phase duration did not significantly impact outcomes.

Conclusions:

• Isoniazid mono-resistance represents a substantial proportion of DRTB, often primary.
• RNTCP treatment regimens for isoniazid mono-resistance are effective but face challenges with high loss to follow-up rates.
• Male gender, age ≥30 years, and prior history of LTFU are associated with poorer treatment outcomes and warrant targeted interventions.