Indications of recall bias found in a retrospective study of physical activity and myocardial infarction.
OBJECTIVE
To evaluate the presence of recall bias in retrospective studies of physical activity and myocardial infarction.


METHODS
In 2005, seventy-eight cases who had suffered from a myocardial infarction and 243 control subjects, who had previously participated in the Swedish WOLF (Work, Lipids, and Fibrinogen) study, were asked about their physical activity level during 1990-2005. The answers about recalled past leisure time, occupational, and household physical activity level were compared with physical activity level as reported at the baseline examination of the WOLF study in 1992-1998.


RESULTS
The proportion who recalled the same activity level as originally reported ranged from 69% to 96% (cases) and 69% to 89% (controls), and the kappa values ranged from 0.30 to 0.91 (cases) and 0.46 to 0.59 (controls), with the exception of perceived physical workload in household work, which showed low agreement between the originally stated and later recalled activity levels. Some differences were found between cases and controls regarding recall of past occupational activity, indicating the presence of recall bias in this domain of physical activity.


CONCLUSIONS
We cannot preclude the existence of recall bias when using retrospectively recalled information about occupational physical activity in studies of physical activity and myocardial infarction.
Fransson
Eleonor
E
Division of Cardiovascular Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm, Sweden. eleonor.fransson@ki.se
Knutsson
Anders
A
Westerholm
Peter
P
Alfredsson
Lars
L
D015982:Bias; D015444:Exercise; D005260:Female; D006801:Humans; D007899:Leisure Activities; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D009043:Motor Activity; D009203:Myocardial Infarction / Q000453:epidemiology*; D012189:Retrospective Studies; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors; D014937:Work