Background: Reversal, or type 1, leprosy reactions (T1Rs) are acute immune episodes that occur in skin and/or nerves and are the leading cause of neurological impairment in patients with leprosy. T1Rs occur mainly in patients with borderline or multibacillary leprosy, but little is known about additional risk factors.
Methods: We enrolled 337 Vietnamese patients with leprosy in our study, including 169 subjects who presented with T1Rs and 168 subjects with no history of T1Rs. A multivariate analysis was used to determine risk factors for T1R occurrence, time to T1R onset after leprosy diagnosis, and T1R sequelae after treatment.
Results: Prevalence of T1Rs was estimated to be 29.1%. Multivariate analysis identified 3 clinical features of leprosy associated with T1R occurrence. Borderline leprosy subtype (odds ratio, 6.3 [95% confidence interval, 2.9-13.7] vs. polar subtypes) was the major risk factor; 2 other risk factors were positive bacillary index and presence of > 5 skin lesions. In addition, age at leprosy diagnosis was a strong independent risk factor for T1Rs (odds ratio, 2.4 [95% confidence interval, 1.3-4.4] for patients aged > or = 15 years old vs. < 15 years old). We observed that T1Rs with neuritis occurred significantly earlier than pure skin-related T1Rs. Sequelae were present in 45.1% of patients who experienced T1Rs after treatment. The presence of a motor or sensory deficit at T1R onset was an independent risk factor for sequelae, as was the age at diagnosis of leprosy (odds ratio, 4.4 [95% confidence interval, 1.7-11.6] for patients > or = 20 years old vs. < 20 years old).
Conclusion: In addition to specific clinical features of leprosy, age is an important risk factor for both T1R occurrence and sequelae after treatment for T1Rs.