The occurrence of reactions and impairments in leprosy: experience in the leprosy control program of three provinces in northeastern Thailand, 1987-1995 [correction of 1978-1995]. II. Reactions.

AIM: This is the second paper in a series of three papers on the occurrence of reactions and impairments in leprosy in Thailand, and focuses on the prevalence and incidence of reactions, including silent neuropathy. STUDY
DESIGN: A population-based, prospective cohort study. STUDY POPULATION: All 640 newly diagnosed and registered leprosy patients in three neighboring provinces in northeastern Thailand registered between October 1987 and September 1990 were included [420 paucibacillary (PB) and 220 multibacillary (MB)]. This group was followed up (actively and passively) until the end of 1995.
METHODS: Clinical data and data on the sensibility and motor function of the eyes, hands and feet were obtained when appropriate. The occurrence of reactions, including silent neuropathy, at the beginning of, during and after treatment was ascertained. During surveillance mild late reactions were also recorded.
RESULTS: Severe reversal reactions (RR) at the start of and during treatment were seen in 2.6% [confidence interval (CI) 1.1-4.1] of the PB and 29% (CI 23-35) of the MB patients. In the PB group the majority (82%) of severe RR were found at the start of treatment. In the MB group 35% of the severe RR were found at the start of treatment and another 59% during the first year of treatment. It is shown that there is a statistically highly significant increasing proportion of patients with severe RR starting from tuberculoid and going toward borderline lepromatous. The incidence rate of severe RR during treatment was 1.4 (CI 0.46-4.5) per 100 person-years at risk (PYAR) for PB patients and 12 (CI 9.0-16) per 100 PYAR for MB patients. Late (mild and severe) RR were seen in 2.7% of the PB and 9% of the MB patients (35% of these reactions being considered severe). Late reactions were mainly seen in borderline tuberculoid (PB group) and in borderline lepromatous patients. Recent silent neuropathies were seen at first examination and during treatment in 1.4% of the pB and 4.1% of the MB patients. During surveillance only a few silent neuropathies were seen. If all severe RR, severe erythema nodosum leprosum and silent neuropathies at the start of, during and after treatment were added together, then 53% of the borderline lepromatous and 42% of the lepromatous patients had or developed one or another serious complication in need of steroid treatment.