Article

Loss to follow-up may bias the outcome assessments of
clinical registries. In this study, we wanted to determine whether outcomes were
different in responding and non-responding patients who were included in a
clinical spine surgery registry, at two years of follow-up. In addition, we wanted to identify risk factors for failure to respond.
METHODS: 633 patients who
were operated for degenerative disorders of the lumbar spine were followed for 2
years using a local clinical spine registry. Those who did not attend the clinic
and those who did not answer a postal questionnaire-for whom 2 years of outcome
data were missing-and who would be lost to follow-up according to the standard
procedures of the registry protocols, were defined as non-respondents. They were
traced and interviewed by telephone. Outcome measures were: improvement in
health-related quality of life (EQ-5D), leg pain, and back pain; and also general
state of health, employment status, and perceived benefits of the operation.
RESULTS: We found no statistically significant differences in outcome between
respondents (78% of the patients) and non-respondents (22%). Receipt of postal
questionnaires (not being summoned for a follow-up visit) was the strongest risk
factor for failure to respond. Forgetfulness appeared to be an important cause.
Older patients and those who had complications were more likely to respond.
INTERPRETATION: A loss to follow-up of 22% would not bias conclusions about
overall treatment effects and, importantly, there were no indications of worse
outcomes in non-respondents.

Langue : ANGLAIS