Sample attrition rate of a community study: An analysis of Lucknow urban and rural elderly follow-up over a period of 9 years

BACKGROUND: Longitudinal/follow-up studies of older adults are a tough task as sample attrition rates due to mortality and other factors may be high in this particular group. However, such studies are very much needed to assess the outcome of health status as well as explore preventive, protective, interventional aspects, as well as risk factors. Given this, a follow-up study was planned and carried out. AIM: To discuss the rate of sample loss as well as the reasons over 9 years. METHODS: An Indian Council of Medical Research (ICMR) supported follow-up study of urban and rural elderly was done during June, 2016–May, 2017; these subjects were studied in 2007-09 through two independent ICMR supported studies. Similar methodology and assessment tools were applied in these studies. During follow-up a semi structured proforma was developed to get the information of study cohort, obtained data was analyzed and presented applying percentage statistics. RESULTS: The sample attrition rate was reported to be comparatively high in urban 52.1% (n= 633) cohort than their rural counterparts 36.3% (n= 457). CONCLUSION: Over a period of 9 years chances of cohort loss due to mortality is about 32%–35%.