Incompleteness of registration data on centenarians in Thailand

Abstract

This study aims to estimate the number of centenarians—the population aged 100 years and over, and to assess the quality of registration data about the elderly population in Thailand. Data were taken from population censuses, life tables constructed from the Survey of Population Change (SPC), regional model life tables, and records in civil registration. Life expectancies of centenarian cohorts were derived from SPC life tables. Model life tables of corresponding levels were applied to determine survival ratios. These ratios were then applied to census population data for 2000 to estimate the number of centenarians still surviving in 2010. These demographic procedures yielded an estimate of about 1,700 surviving centenarians in 2010, which was only 12 percent of the number recorded in official civil registration figures. The inflated estimates of the centenarian population recorded by the civil registration system were investigated by in-depth interviews of the centenarians, village/sub-district headmen, registrars, and relatives of deceased persons in two selected provinces. Names and addresses of centenarians were acquired from civil registration and were followed up to evaluate their accuracy. It was found from this study that incompleteness of death registration and incorrect age recording were the main causes of the inflated figures of centenarians found in registration data in Thailand.