The effect of multiple reminders on response patterns in a Danish health survey.

BACKGROUND: Reminders are routinely applied in surveys to increase response rates and reduce the possibility of bias. This study examines the effect of multiple reminders on the response rate, non-response bias, prevalence estimates and exposure-outcome relations in a national self-administered health survey. METHODS: Data derive from the Danish National Health Survey 2010, in which 298,550 individuals (16 years of age or older) were invited to participate in a cross-sectional survey using a mixed-mode approach (paper and web questionnaires). At least two reminders were sent to non-respondents, and 177,639 individuals completed the questionnaire (59.5%). Response patterns were compared between four groups of individuals (first mailing respondents, second mailing respondents, third mailing respondents and non-respondents). RESULTS: Multiple reminders led to an increase in response rate from 36.7 to 59.5%; however, the inclusion of second and third mailing respondents did not change the overall characteristics of respondents compared with non-respondents. Furthermore, only small changes in prevalence estimates and exposure-outcome relationships were observed when including second and third mailing respondents compared with only first mailing respondents. CONCLUSIONS: Multiple reminders were an effective way to increase the response rate in a national Danish health survey. However, when differences do exist between respondents and non-respondents, the results suggest that second and third mailings are unlikely to eliminate these differences. Overall, multiple reminders seemed to have only minor effect on response patterns and study conclusions in the present study.

Social marginalization reduces use of ENT physicians in primary care.

OBJECTIVE: The aim of this study was to explore the association between social marginalization of the mothers and their children's use of the healthcare system and ear-nose-throat (ENT) physicians in the year 2009 in a region of Denmark. METHODS: A regional register-based cross-sectional study of use of healthcare services among children (n=10,232) of marginalized mothers and children (n=101,582) of non-marginalized mothers in the North Denmark Region. Social marginalization was defined as having received public social benefits for more than 80% of the year. RESULTS: Children with a marginalized mother had more chronic medical diagnoses (OR=1.22, 95% confidence interval 1.17-1.28), they had more frequently been in contact with their general practitioner during the year, and they used the healthcare system more often than children of non-marginalized mothers, except in the case of ENT specialists (OR=0.90, 0.85-0.95), and they had more seldom tympanostomy tubes inserted (OR=0.75, 0.66-0.87). The distance between ENT-clinic and place of residence of the patients had only a small effect on the use of ENT-physician, and only significant in the non-marginalized. CONCLUSIONS: Children of marginalized mothers used the healthcare system more than other children, except in case of ENT-physicians. They had fewer ENT-consultations and had less frequently inserted tympanostomy tubes when they attended the surgery.