Factors relating to participation in follow-up to the 45 and up study in Aboriginal and non-Aboriginal individuals

Abstract

BackgroundThis study aimed to characterise the factors relating to participation in a postal follow-up study in Aboriginal and non-Aboriginal individuals, given the need to quantify potential biases from loss to follow-up and the lack of evidence regarding postal surveys among Aboriginal people.MethodsThe first 100,000 participants from the Sax Institute’s 45 and Up Study, a large scale cohort study, were posted a follow-up questionnaire gathering general demographic, health and risk factor data, emphasising Social, Economic and Environmental Factors (“The SEEF Study”). For each variable of interest, percentages of those invited who went on to participate in follow-up were tabulated separately for Aboriginal and non-Aboriginal participants and age- and sex-adjusted participation rate ratios (aPRR) were calculated.ResultsOf the 692 Aboriginal and 97,178 non-Aboriginal invitees to the study, 314 Aboriginal (45 %) and 59,175 non-Aboriginal (61 %) individuals responded. While Aboriginal people were less likely to respond than non-Aboriginal people (aPRR 0.72, 95 % CI 0.66–0.78), factors related to response were similar. Follow-up study participants were more likely than non-participants to have university versus no educational qualifications (1.6, 1.3–2.0 [Aboriginal]; 1.5, 1.5–1.5 [non-Aboriginal]) and an annual income of ≥70,000 versus < $20,000 (1.6, 1.3–2.0; 1.2, 1.2–1.3 [χ2 = 7.7; p = 0.001]). Current smokers (0.55, 0.42–0.72; 0.76, 0.74–0.77 [χ2 = 7.14; p = 0.03]), those reporting poor self-rated health (0.68, 0.47–0.99; 0.65, 0.61–0.69), poor quality of life (0.63, 0.41–0.97; 0.61, 0.57–0.66) and very high psychological distress (0.71, 0.68–0.75 [non-Aboriginal]) were less likely than other cohort members to respond.ConclusionsRelatively large numbers of Aboriginal and non-Aboriginal individuals participated in the first 45 and Up Study follow-up suggesting that postal surveys can be used to follow Aboriginal participants in cohort studies. Despite somewhat greater loss to follow-up in Aboriginal people (after considering socio-demographic and health characteristics), factors related to follow-up participation were similar in both groups: greater loss was observed in those experiencing disadvantage, ill-health and health risk, with implications for interpretation of future findings. Aboriginal low income earners and current regular smokers had a particularly elevated likelihood of non-participation compared to non-Aboriginal people. These findings highlight the importance of identifying and addressing barriers to participation among hard-to-reach population groups.Electronic supplementary materialThe online version of this article (doi:10.1186/s12874-016-0155-x) contains supplementary material, which is available to authorized users.

A Prospective Study of Health Conditions Related to Alcohol Consumption Cessation Among 97,852 Drinkers Aged 45 and Over in Australia

“…A limitation is that 57% of current drinkers at baseline completed follow‐up, which has potential to induce selection bias. Specifically, participants who completed the follow‐up questionnaire may be healthier than those who did not (Gubhaju et al., ), which may mean our estimates of the effects of ill‐health on quitting are conservative. This is shown in Table where participants included in the analysis were healthier and of higher socioeconomic status compared to all drinkers at baseline.…”

Relationship Between Midlife Cardiovascular Health and Late‐Life Physical Performance: The ARIC Study

“…Loss to follow‐up was substantial over 25 years, as happens with cohort studies. Participants with poor function are more likely to drop out over time . To account for informative missingness, the analysis included those with missing functional performance data in the group with poorest function.…”

“…Participants with poor function are more likely to drop out over time. 36,37 To account for informative missingness, the analysis included those with missing functional performance data in the group with poorest function. Results from complete case analysis models are also presented, ignoring participants with missing functional performance, and substantively the same albeit attenuated relationships were found.…”

‘Telling our story... Creating our own history’: caregivers’ reasons for participating in an Australian longitudinal study of Indigenous children

“…It is challenging in any population to retain participants in a longitudinal study [ 11 , 12 ], which may have implications for the validity of the data and findings. There is some evidence that retention rates are lower for Aboriginal and/or Torres Strait Islander participants compared to non-Indigenous participants in large-scale Australian longitudinal studies [ 13 – 16 ]. For example, retention of Aboriginal participants at the first wave of follow-up in the 45 and Up Study was significantly lower than retention of non-Aboriginal participants (45% versus 61%; age-sex-adjusted participation rate ratio 0.72, 95%CI:0.66,0.78) [ 16 ].…”

“…There is some evidence that retention rates are lower for Aboriginal and/or Torres Strait Islander participants compared to non-Indigenous participants in large-scale Australian longitudinal studies [ 13 – 16 ]. For example, retention of Aboriginal participants at the first wave of follow-up in the 45 and Up Study was significantly lower than retention of non-Aboriginal participants (45% versus 61%; age-sex-adjusted participation rate ratio 0.72, 95%CI:0.66,0.78) [ 16 ]. Lower retention rates may reflect additional barriers to research participation for Aboriginal and Torres Strait Islander, compared to non-Indigenous, Australians.…”