Large-scale cohort studies are valuable for quantifying associations between potential risk factors and mortality outcomes.

However, the representativeness of cohort studies can vary, potentially influencing the resulting estimates of association.

Here, we considered data from the large Australian 45 and Up Study cohort.

We assessed the impact of weighting on the associations between participants’ characteristics and key mortality outcomes.

Our study supports the generalisability of most associations in the 45 and Up Study data, particularly for cancer mortality.

Weighting can improve study estimate representativeness. We examined the impact of weighting on associations between participants’ characteristics and cancer, cardiovascular and all-cause mortality in the Australian 45 and Up Study cohort.

Raking weighted cohort data to the 2006 Australian population for seven sociodemographic characteristics. Deaths were ascertained via linkage to routinely collected data. Cox’s proportional hazards regression quantified associations between 11 sociodemographic and health characteristics and cancer, cardiovascular and all-cause mortality. The ratios of hazard ratios (RHRs) compared unweighted and weighted estimates.

Among 195,052 included participants (median follow-up 11.4 years), there were 7200 cancer, 5912 cardiovascular and 21,840 all-cause deaths. Overall, 102/111 (91.9%) weighted HRs did not differ significantly from unweighted HRs (100%, 86.5% and 89.2% of 37 HRs for cancer, cardiovascular and all-cause mortality, respectively). Significant differences included a somewhat stronger association between single/widowed/divorced (versus married/de-facto) and cardiovascular mortality (unweighted HR=1.25 (95%CI:1.18–1.32), weighted HR=1.33 (95%CI:1.24–1.42), RHR=1.06 (95%CI:1.02–1.11)); and between no school certificate/qualification (versus university degree) and all-cause mortality (unweighted HR=1.21 (95%CI:1.15–1.27), weighted HR=1.28 (95%CI:1.19–1.38), RHR=1.06 (95%CI:1.03–1.10)).

Our results support the generalisability of most estimates of associations in the 45 and Up Study, particularly in relation to cancer mortality. Slight distortion of a few associations with cardiovascular or all-cause mortality were observed.

Centre for Health Record Linkage

Moderate to Vigorous Physical Activity

Ratio of Hazard Ratios

Raking weighting

45 and Up Study

Risk factors

Mortality

Cardiovascular mortality

Cancer mortality

Australia

© 2024 The Daffodil Centre. Published by Elsevier Ltd.