Socioeconomic position and participation in baseline and follow-up visits: the Inter99 study

Abstract

Background:

The aim of this paper was to identify the extent of socioeconomic inequality in participation at baseline and follow-up visits.

Design:

The Inter99 study is a randomized intervention with the aim of investigating the effects of an individualized lifestyle consultation on ischaemic heart disease (IHD). The study comprised 61,301 persons of which 13,016 were assigned to the intervention group. The rest formed the control group. All those in the intervention group were invited to participate in health examinations, risk assessments, and lifestyle consultations. Participants at high risk of IHD were invited to follow-up visits after 1, 3, and 5 years.

Methods:

Data on five socioeconomic factors were retrieved from nationwide registers. For each socioeconomic factor we estimated the relative risks and relative index of inequality of participation at the baseline visit and among high-risk participants at follow-up visits. In addition, we conducted analyses of trends in socioeconomic inequality in participation across follow-up visits.

Results:

Participation rates were 53% at baseline and 61–65% at the three follow-up visits. There was strong socioeconomic inequality in participation at baseline, with increasing probability of participation found with increasing level of socioeconomic position. This was smaller at follow-up visits. Except for education and housing tenure, there was an increase in socioeconomic inequality in participation across follow-up visits.

Conclusions:

We found strong socioeconomic inequality in participation at baseline and follow-up visits. Effort should be made to increase participation in individualized lifestyle interventions among persons of low socioeconomic position. Otherwise, the consequence may be increased socioeconomic inequality in IHD.

Keywords

Follow-up study high risk ischaemic heart disease lifestyle intervention participation register-based data socioeconomic position

Get full access to this article

View all access options for this article.

References

Harper

Lynch

Smith

. Social determinants and the decline of cardiovascular diseases: understanding the links. Annu Rev Public Health 2011; 32: 39–69.

Fifth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (constituted by representatives of nine societies and by invited experts)European Guidelines on cardiovascular disease prevention in clinical practice (version 2012). Eur J Prev Cardiol 2012; 19: 585–667.

Mackenbach JP. Health inequalities: Europe in profile. UK Presidency of the EU, 2006. London: COI (Central Office of Information).

Ebrahim

Taylor

Ward

. Multiple risk factor interventions for primary prevention of coronary heart disease. Cochrane Database Syst Rev 2011; 1: CD001561–CD001561.

Berglund

Nilsson

Eriksson

. Long-term outcome of the Malmo preventive project: mortality and cardiovascular morbidity. J Intern Med 2000; 247: 19–29.

Eriksen

Grønbaek

Helge

. The Danish Health Examination Survey 2007–2008 (DANHES 2007–2008). Scand J Public Health 2011; 39: 203–211.

Søgaard

Selmer

Bjertness

. The Oslo Health Study: the impact of self-selection in a large, population-based survey. Int J Equity Health 2004; 3: 3–3.

Strandhagen

Berg

Lissner

. Selection bias in a population survey with registry linkage: potential effect on socioeconomic gradient in cardiovascular risk. Eur J Epidemiol 2010; 25: 163–172.

Tjønneland

Olsen

Boll

. Study design, exposure variables, and socioeconomic determinants of participation in Diet, Cancer and Health: a population-based prospective cohort study of 57,053 men and women in Denmark. Scand J Public Health 2007; 35: 432–441.

10.

Wilhelmsen

Tibblin

Werkö

. (1972) A primary preventive study in Gothenburg, Sweden. Prev Med 2007; 1: 153–160.

11.

Inelmen

Toffanello

Enzi

. Predictors of drop-out in overweight and obese outpatients. Int J Obes 2005; 29: 122–128.

12.

Archer

Rinzler

Christakis

. Social factors affecting participation in a study of diet and coronary heart disease. J Health Soc Behav 1967; 8: 22–31.

13.

McCann

Criqui

Kashani

. A randomized trial of cardiovascular risk factor reduction: patterns of attrition after randomization and during follow-up. J Cardiovasc Risk 1997; 4: 41–46.

14.

Merrill

Aldana

. Cardiovascular risk reduction and factors influencing loss to follow-up in the coronary health improvement project. Med Sci Monit 2008; 14: H17–H25.

15.

Jørgensen

Borch-Johnsen

Thomsen

. A randomized non-pharmacological intervention study for prevention of ischaemic heart disease: baseline results Inter99. Eur J Cardiovasc Prev Rehabil 2003; 10: 377–386.

16.

Thomsen

Davidsen

Ibsen

. A new method for CHD prediction and prevention based on regional risk scores and randomized clinical trials; PRECARD and the Copenhagen Risk Score. J Cardiovasc Risk 2001; 8: 291–297.

17.

Sundararajan

Henderson

Perry

. New ICD-10 version of the Charlson comorbidity index predicted in-hospital mortality. J Clin Epidemiol 2004; 57: 1288–1294.

18.

Mackenbach

Kunst

. Measuring the magnitude of socio-economic inequalities in health: an overview of available measures illustrated with two examples from Europe. Soc Sci Med 1997; 44: 757–771.

19.

Watt

. The inverse care law today. Lancet 2002; 360: 252–254.

20.

Ludt S, Wensing M, Campbell SM, et al. The challenge of cardiovascular prevention in primary care: implications of a European observational study in 8928 patients at different risk levels. Eur J Prev Cardiol 2012 [Epub ahead of print].

21.

Aadahl

von Huth

Toft

. (2011) Does a population-based multi-factorial lifestyle intervention increase social inequality in physical activity? The Inter99 study. Br J Sports Med 2012; 45: 209–215.

22.

Toft

Jakobsen

Aadahl

. Does a population-based multi-factorial lifestyle intervention increase social inequality in dietary habits? The Inter99 study. Prev Med 2011; 54: 88–93.

23.

Pisinger

Aadahl

Toft

. Does a population-based multi-factorial lifestyle intervention increase social inequality in smoking? The Inter99 study. OJPM3: 394–402.

24.

Lorent

Deliège

Eaton

. (2003) Socioeconomic inequalities in depression: a meta-analysis. Am J Epidemiol 2012; 157: 98–112.