Under-reporting of inpatient services utilisation in household surveys – a population-based study in Hong Kong

Territory-wide inpatient service utilisation volumes as estimated from the 1999, 2001 and 2002 Thematic Household Surveys (THS) were benchmarked against corresponding statistics derived from routine administrative databases. Between-year differences on net under-reporting were quantified by Cohen's d effect size. To assess the potential for systematic biases in under-reporting, age- and sex-specific net under-reporting rates within each survey year were computed and the F-test was performed to evaluate differences between demographic subgroups. We modelled the effects of age and sex on the likelihood of ever hospitalisation through logistic regression to compare the odds ratios respectively derived from survey and administrative data.The extent of net under-reporting was moderately large in all three years amounting to about one-third of all inpatient episodes. However, there did not appear to be significant systematic biases in the degree of under-reporting by age or sex on stratified analyses and logistic regression modelling.Under-reporting was substantial in Hong Kong's THS. Recall bias was likely most responsible for such reporting inaccuracies. A proper full-design record-check study should be carried out to confirm the present findings.Population and health services research commonly relies on in-person household interviews as the main source of health and health care data, in terms of disease, disability and utilisation of services. These types of information are important for evidence-based health policy formulation, planning and evaluation. While medical chart review, insurance claims records and government macro statistics are potential alternative sources of such information, they cannot entirely replace the household interview given the often prohibitive expense of data abstraction exercises, lack of population coverage of single data sources especially in a mixed medical economy where there is a multiplicity of financial intermediaries and care provide