Evaluation of non-response in quality control of nasal septal surgery

Questionnaires are often used to assess the results of nasal septoplasty, but response rates vary widely. The possible bias caused by non-responders was evaluated to determine the validity of questionnaire results.

Post-operative questionnaires employing visual analogue scales for nasal obstruction were mailed to 182 patients. The 62 non-responders (34.1 per cent) were contacted by telephone, 58 (93.5 per cent) of whom were contactable and responded orally to the questionnaire.

Non-responders were younger, but no different from responders with regard to gender, smoking habits or allergies. Post-operative visual analogue scale obstruction scores were slightly, but not statistically, higher in non-responders. However, because non-responders' pre-operative scores were lower, obstruction scores improved less than in responders. The main reason for not responding was forgetfulness. Some would have preferred an electronic version of the questionnaire.

Although post-operative obstruction scores did not differ between the groups, nasal obstruction scores improved more among responders than non-responders. Thus, low response rates may cause bias.