Methodological challenges and approaches to improving response rates in population surveys in areas of extreme deprivation.

Achieving good response rates to population surveys from hard to reach groups in deprived areas can be challenging. To explore and compare different approaches to improving response rates in an economically deprived multicultural area. Following a lower than anticipated response rate in a pilot study for a postal questionnaire survey of chronic pain (79/653 (12%)), we conducted a second pilot involving a shorter postal survey and separate collection of more detailed information in a waiting room survey. The second postal survey used a shorter questionnaire, telephone data collection from non-responders by study team members rather than telephone reminders from practice receptionists, and involved a nested randomised-controlled trial (RCT) of hand-addressed versus printed-address envelopes. Both pilots involved subjects randomly selected from the practice registers. The second pilot postal survey using shorter questionnaires yielded considerably more responses (240/642 (37%)). Our RCT showed that hand-addressed envelopes achieved a slightly higher response rate although not large enough to justify its use in our main study. The waiting room survey was successful in collecting more detailed data from lengthy questionnaires. A range of methods of questionnaire administration may be required when conducting a survey with a hard to reach group in a deprived and ethnically diverse population. Postal and telephone administration can be used to collect a small amount of data. Face-to-face administration and recruitment can be successful for longer questionnaires.