Article

Non-response is a serious threat to the external validity of longitudinal
psychosocial studies. Little is known about potential systematic differences
between patients with coronary artery disease who complete a psychosocial study
and those who drop out prematurely due to non-response, or whether drop-outs may
have a different cardiovascular risk. We studied a cohort of 1132 consecutive
patients undergoing percutaneous coronary intervention (PCI). At baseline, all
patients completed the Hospital Anxiety and Depression Scale (HADS) and the Type
D Scale (DS14). At 12 months follow-up, 70.8% (n = 802) of patients completed
both questionnaires, while 29.2% (n = 330) dropped out. We observed significant
differences in socio-demographic, clinical, and psychological baseline
characteristics between completers and drop-outs. Drop-outs were younger, more
likely to smoke, but less often prescribed cardiovascular medications, including
calcium antagonists and angiotensin-converting enzyme inhibitors, as compared
with completers. Drop-outs more often had depression, anxiety, and negative
affectivity, as compared with completers (all p-values <0.05). After a median
follow-up of 4 years, we found no significant differences in mortality risk
between completers and drop-outs (6.5 vs. 7.3%; adjusted HR 1.34, 95% CI
0.82-2.19, respectively). In conclusion, a possible attrition bias occurred, as
drop-outs and completers differed systematically on some socio-demographic,
clinical, and psychological baseline characteristics. Despite these differences,
this did not translate into a poorer short-term prognosis, as there were no
differences in the mortality risk of completers vs. drop-outs after a median
follow-up of 4 years. In future prospective studies, attention should be paid to
attrition bias, and its possible impact on study results and implications should
be discussed.
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Langue : ANGLAIS