SciELO - Scientific Electronic Library Online

 
vol.20 issue4Biosecurity: behavior of dental students in control of cross infectionTime series of renal cancer mortality in Brazil (1996-2010) author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand

Journal

Article

Indicators

Related links

Share


Cadernos Saúde Coletiva

Print version ISSN 1414-462X

Abstract

COELI, Cláudia Medina et al. Exploring the effects of non-response to the baseline and follow-up on the validity in cohort studies. Cad. saúde colet. [online]. 2012, vol.20, n.4, pp.533-536. ISSN 1414-462X.  http://dx.doi.org/10.1590/S1414-462X2012000400018.

Few articles have evaluated the effects of non-response in cohort studies. The aim of this study was to assess if non-response, both to the baseline and to follow-up, may introduce selection bias on the association between occupational level and mortality. There were applied the non-response and mortality estimates of the Whitehall II study to a hypothetical cohort encompassing 110.000 person-years (occupational level: low - 50,000; high - 60,000). There were considered four scenarios: (1) full participation; (2) non-response to baseline; (3) non-response to follow-up; (4) non-response to baseline and follow-up. There were calculated mortality rate ratios (RR) considering the high occupation level as reference and absence of confounding or information bias. The first scenario RR was 1.79, with only the last scenario showing an important impact of the non-response on the rate ratio estimate (RR=1.2). The results suggest that combining non-response in different stages of cohort studies may cause selection bias.

Keywords : cohort studies; refusal to participate; selection bias.

        · abstract in Portuguese     · text in Portuguese     · Portuguese ( pdf )

 

Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License