The link between major risk factors and important categories of admission in an ageing cohort

Record linkage of routine hospital data to population-based research findings presents an opportunity to explore the relationships between classical risk factors and hospital activity.

The objectives of this study were to examine, in Paisley and Renfrew, the effect of risk factor variables on the likelihood of experiencing an acute hospital admission with six major medical conditions. The subjects were 8,349 women and 7,057 men, aged 45-64 in the early to mid-1970s. The main outcome measures were acute hospital admission with principal diagnosis of: any malignant neoplasm; malignant neoplasm of trachea, bronchus and lung; ischaemic heart disease; respiratory disease; cerebrovascular disease; or diabetes mellitus.

Smokers were almost eight times more likely to be admitted with lung cancer and, to a lesser extent, were more likely to be admitted for the other conditions investigated with the exception of diabetes mellitus. Forced expiratory volume was also an independent risk factor for admission with lung cancer and strokes. Higher levels of cholesterol were associated with increased risk of admission with ischaemic heart disease but less with cancer (including lung cancer). With the exception of admissions for cerebrovascular disease, deprivation category was found to have no independent effect on the likelihood of experiencing any of the morbidity outcomes examined.

These data confirm that associations first established between risk factors and mortality outcomes (e.g. smoking and lung cancer) are also found between risk factors and hospital admissions for the same causes. This in itself is unremarkable, but the results are of interest for three reasons. First, they illustrate the potential of record linkage to map the effects of risk factors. Second, they demonstrate the size of the effect risk factors have on the risk of admission. Third, they provide a surprising finding that deprivation category does not act as an independent risk factor for the majority of the categories of admission investigated.