The development of a new measure of quality of life for young people with diabetes mellitus: the ADDQoL-Teen

BACKGROUND This study evaluated the psychometric properties of the ADDQoL-Teen, an innovative individualised, patient-centred questionnaire measuring perceived impact of diabetes mellitus on quality of life (QoL) of teenagers. Respondents rate all 30 life domains for frequency, and personally applicable domains for 'bother'. Two overview items measure present QoL and diabetes-dependent QoL. ADDQoL-Teen design was based on the ADDQoL (for adults with diabetes). METHODS Interviews and discussion groups were conducted with 23 teenagers aged 13-16 years, during work to design the ADDQoL-Teen. The new questionnaire was then completed by 152 young people, (mean age 16.4 +/- 2.4 years), attending diabetes clinics at six UK centres. RESULTS Five domains detracted from the measure's reliability and factor structure, four of which were analysed separately and one deleted. The 25-domain ADDQoL-Teen had high internal consistency reliability [Cronbach's alpha = 0.91, (N = 133)] and could be summed into an overall Average Weighted Impact score. There were two subscales: a 10-item Impact-Self subscale (measuring impact of diabetes and its treatment on the individual) and a 15-item Impact-Other subscale (measuring impact on interactions with others and the external world). Both subscales had good internal consistency reliability, [Cronbach's alpha coefficients of 0.82 (N = 142) and 0.88 (N = 138) respectively]. Domains reported as most severely (and negatively) impacted by diabetes were (mean weighted impact +/- SD): lie in bed (-3.68 +/- 3.41), interrupting activities (-3.5 +/- 3.23), worry about the future (-3.45 +/- 3.28), career (-3.43 +/- 3.15) and sweets (-3.24 +/- 3.24), (maximum range -9 to +3). Analysis of the overview items showed that although 72.5% considered that their present QoL was good or brilliant, 61.8% felt that having diabetes had a negative impact on QoL, but 35.6% reported no impact and 2.6% reported a positive impact on QoL. CONCLUSIONS The ADDQoL-Teen is a new measure of perceived impact of diabetes and its treatment on QoL of teenagers. It will help healthcare professionals and parents consider QoL issues as well as medical outcomes when caring for young people with diabetes. It may be used in clinical trials and for routine clinical monitoring in a context of continuing evaluation.