Measuring the physical and economic impact of filarial lymphoedema in Chikwawa district,Malawi:a case-control study

摘要

Background:Lymphatic filariasis(LF)is one of the primary causes of lymphoedema in sub-Saharan Africa,and has a significant impact on the quality of life(QoL)of those affected.In this paper we assess the relative impact of lymphoedema on mobility and income in Chikwawa district,Malawi.Methods:A random sample of 31 people with lymphoedema and 31 matched controls completed a QoL questionnaire from which both an overall and a mobility-specific score were calculated.Two mobility tests were undertaken,namely the 10 m walking test[10MWT]and timed up and go[TUG]test,and a subset of 10 casescontrol pairs wore GPS data loggers for 3 weeks to measure their mobility in a more natural setting.Retrospective economic data was collected from all 31 case-control pairs,and each participant undertaking the GPS activity recorded daily earnings and health expenditure throughout the observation period.Results:Cases had a significantly poorer overall QoL(cases=32.2,controls=6.0,P<0.01)and mobility-specific(cases=43.1,controls=7.4,P<0.01)scores in comparison to controls.Cases were also significantly slower(P<0.01)at completing the timed mobility tests,e.g.mean 10MWT speed of 0.83 m/s in comparison to 1.10 m/s for controls.An inconsistent relationship was observed between mobility-specific QoL scores and the timed test results for cases(10MWT correlation=−0.06,95%CI=(−0.41,0.30)),indicating that their perceived disability differed from their measured disability,whereas the results were consistent for controls(10MWT correlation=−0.61,95%CI=(−0.79,−0.34)).GPS summaries indicated that cases generally walk shorter distances at slower speeds than control,covering a smaller geographical area(median area by kernel smoothing:cases=1.25 km2,controls=2.10 km^(2),P=0.16).Cases reported earning less than half that earned by controls per week(cases=$0.70,controls=$1.86,P=0.064),with a smaller proportion of their earnings(16%vs 22%,P=0.461)being spent on healthcare.Conclusions:Those affected by lymphoedema are at a clear disadvantage to their unaffected peers,experiencing a lower QoL as confirmed by both subjective and objective mobility measures,and lower income.This study also indicates that objective measures of mobility may be a useful supplement to self-assessed QoL questionnaires when assessing the future impact of lymphoedema management interventions.