Groeneveld et al. BMC Public Health 2011, 11:836 http://www.biomedcentral.com/1471-2458/11/836 to smoke than the participants [39]. The differences between the target group and the study completers may slightly lower the generalizability of the results. Neverthe- less, the age- and lifestyle-related characteristics of the drop-outs were equal in the intervention and the control group. Last, by analyzing the EB and SC group separately, the study may have become underpowered. Since differ- ences between intervention and control group were checked and adjusted for, both within the EB and SC groups, no confounding will have occurred. This study also has numerous strengths. Compliance to the interven- tion was rather high, i.e. two-thirds of participants in the intervention group had five or more counseling sessions [40]. Only few participants in the control group had received lifestyle advice from another care provider, thus the contrast between groups was large. Randomization was performed at the individual level, which is the pre- ferred method since baseline differences between interven- tion and control group are least likely. With respect to the analyses, the participants in the EB group were analyzed separately from those in the SC group, in order to deter- mine changes in the lifestyle behaviors that were actually aimed at. Furthermore, the study can be considered as an effectiveness study as opposed to an efficacy study. Namely, counseling was conducted at the occupational health service and performed by an occupational health service professional instead of by the researchers them- selves. As the results of this study reflect the intervention effectiveness in ‘real life’, decision makers will better be able to decide upon implementation. The most important strength is that we investigated the effects on CVD risk- related behaviors no less than 6 months after the interven- tion had ended. With this study, we generated knowledge on the effectiveness of a promising counseling strategy on behavior change among a population in which CVD risk will be rising in the following years. Conclusions We conclude that this lifestyle intervention for workers in the construction industry at risk for CVD had signifi- cant effects on snack and fruit intake and smoking at 6 months. The significant effects on snack intake were unchanged at the long term. Future studies should be done on strategies for changing leisure time PA, and on determinants of maintenance of changed behavior in this population. Considering the rising prevalence of unhealthy lifestyle and CVD, especially in the aging population, implementation of this intervention in the occupational health care setting is recommended. Acknowledgements We are grateful to Stichting Arbouw for covering the study costs. We would like to acknowledge Mrs. S. Absalah for collecting the data. Page 8 of 9 Author details 1Department of Public and Occupational Health, EMGO+ Institute for Health and Care Research, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands. 2Body@Work, Research Center Physical Activity, Work and Health, TNO-VUmc, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands. 3TNO Quality of Life, Department of Physical Activity and Health, Wassenaarseweg 56, 2301 CE Leiden, The Netherlands. Authors’ contributions IG performed the analyses and wrote the manuscript. KP wrote the original study protocol. KP, AB, VH and WM provided intellectual input and had a role in supervision. All authors read and approved the final manuscript. Competing interests Statement The authors declare that they have no competing interests. Received: 19 May 2011 Accepted: 31 October 2011 Published: 31 October 2011 References 1. Vaartjes I, Peters RJG, Van Dis SJ, Bots ML: Hart- en vaatziekten in Nederland 2008, cijfers over ziekte en sterfte. Den Haag: Nederlandse Hartstichting; 2008. 2. Yu DS, Lee DT, Kwong AN, Thompson DR, Woo J: Living with chronic heart failure: a review of qualitative studies of older people. J Adv Nurs 2008, 61:474-483. 3. Mente A, de KL, Shannon HS, Anand SS: A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease. Arch Intern Med 2009, 169:659-669. 4. Lee CD, Folsom AR, Blair SN: Physical activity and stroke risk: a meta- analysis. Stroke 2003, 34:2475-2481. 5. Mancia G, Groppelli A, Casadei R, Omboni S, Mutti E, Parati G: Cardiovascular effects of smoking. Clin Exp Hypertens 1990, 12:917-929. 6. Hintsa T, Shipley M, Gimeno D, Elovainio M, Chandola T, Jokela M, et al: Do pre-employment influences explain the association between psychosocial factors at work and coronary heart disease? The Whitehall II study. Occup Environ Med 2009. 7. Ebrahim S, Beswick A, Burke M, Davey SG: Multiple risk factor interventions for primary prevention of coronary heart disease. Cochrane Database Syst Rev 2006, 18:CD001561. 8. Elmer PJ, Obarzanek E, Vollmer WM, Simons-Morton D, Stevens VJ, Young DR, et al: Effects of comprehensive lifestyle modification on diet, weight, physical fitness, and blood pressure control: 18-month results of a randomized trial. Ann Intern Med 2006, 144:485-495. 9. Lindstrom J, Louheranta A, Mannelin M, Rastas M, Salminen V, Eriksson J, et al: The Finnish Diabetes Prevention Study (DPS): Lifestyle intervention and 3- year results on diet and physical activity. Diabetes Care 2003, 26:3230-3236. 10. Brown T, Avenell A, Edmunds LD, Moore H, Whittaker V, Avery L, et al: Systematic review of long-term lifestyle interventions to prevent weight gain and morbidity in adults. Obes Rev 2009, 10:627-638. 11. Sodlerlund A, Fischer A, Johansson T: Physical activity, diet and behaviour modification in the treatment of overweight and obese adults: a systematic review. Perspect Public Health 2009, 129:132-142. 12. Rubak S, Sandboek A, Lauritzen T, Christensen B: Motivational interviewing: a systematic review and meta-analysis. Br J Gen Pract 2005, 55:305-312. 13. Van Dorsten B: The use of motivational interviewing in weight loss. Curr Diab Rep 2007, 7:386-390. 14. Miller WR, Rollnick S: Motivational Interviewing; preparing people for change116. 2 edition. New York: The Guilford Press; 2002. 15. Godin G, Kok G: The theory of planned behavior: a review of its applications to health-related behaviors. Am J Health Promot 1996, 11:87-98. 16. Proper KI, van den Heuvel SG, De Vroome EM, Hildebrandt VH, van der Beek AJ: Dose-response relation between physical activity and sick leave. Br J Sports Med 2006, 40:173-178. 17. Ilmarinen JE: Aging workers. Occup Environ Med 2001, 58:546-552. 18. Nilsson PM, Klasson EB, Nyberg P: Life-style intervention at the worksite– reduction of cardiovascular risk factors in a randomized study. Scand J Work Environ Health 2001, 27:57-62.