Aim: This the third 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 neural and other impairments in leprosy.
Study design: A population-based, prospective cohort study. STUDY SUBJECT: All 640 newly diagnosed and registered leprosy patients in three provinces of northeastern Thailand between October 1987 and September 1990 were included [420 paucibacillary (PB) and 220 multibacillary (MB)]. This group of patients was followed up until the end of 1995.
Methods: Clinical data; data on the sensibility and motor function of eyes, hands and feet, and data on wounds and bone loss were obtained where appropriate. The occurrence of neural and other impairments at first examination, during treatment and during surveillance was ascertained.
Results: The relationship between impairment prevalence (grade 2 of the combined PB and MB groups and grades 1 and 2 together of the combined PB and MB groups) and duration of disease (before diagnosis) was found to be statistically significant. Increased delay in detection led to increased problems of impairments. Too many patients still develop new/additional impairments while on treatment and thereafter. The incidence of nerve function impairment (NFI) among patients without impairments at first examination while on treatment was 1.7 [ 95% confidence interval (CI) 0.45-4.4] per 100 person-years at risk (PYAR) for the PB group and 12 (CI 8.4-17) per 100 PYAR for the MB group. Additionally, 2% of the PB and 11% of the MB patients who already had impairments at first examination developed new NFI while on treatment. The outcome, comparing the first examination with the last examination during/after surveillance [changes in the voluntary muscle test (VMT), the sensory test (ST), wound count and bone loss], indicated that of the PB patients 3.7% improved, 3.7% got worse and 3.9% kept the same impairment; of the MB patients 19% improved, 18% got worse and 2.9% kept the same impairment. During treatment most of the new/additional impairments were due to new/increase in NFI; during surveillance slightly more than 50% were due to new/increase in NFI. Eighty-three percent of the MB patients without impairments at first examination who developed NFI during treatment improved (completely or partially) after receiving prednisolone. Only 62% of the MB patients with a grade 1 impairment at first examination and who developed a severe reaction or recent silent neuropathy improved after receiving prednisolone. There is a need for an indicator to measure new/additional impairments while on treatment and thereafter. It is proposed to measure changes in impairment by measuring changes in VMT, ST, wound count and bone loss.