Optimising response rates in a national postal survey evaluating community mental health care: four interventions trialled.

BACKGROUND The Community Mental Health Survey (CMHS) is a valuable resource of information on experiences of mental health care in England; however, response rates are declining. AIM To increase the overall response rate and response rate of young adult service users. METHODS Four interventions were trialled in a randomised controlled study design alongside the 2017 CMHS. The questionnaire and information letters were modified based on an established framework for influencing behaviour. The modified materials plus a pre-notification card were tested to increase the overall response rate, identified by one-sided z-tests between the intervention and control groups. An information flyer was modified to target service users age 18 to 35, tested using multilevel logistic regression. RESULTS The overall response rate significantly increased with the modified information letters compared to the control (29.1% vs. 25.1%; p = 0.007). The targeted information flyer did not increase responses from younger service users; though the combination of modified information letters and questionnaire did (24.6% vs. 15.8%; p = 0.01). CONCLUSIONS Modifying information letters based on the easy, attractive, social and timely (EAST) framework can increase response rate in postal surveys evaluating community mental health care. Modified letters combined with a modified questionnaire can increase the response from younger service users.