1. Introduction ESTIMATING THE MINIMALLY IMPORTANT DIFFERENCE (MID) OF THE DIABETES HEALTH PROFILE (DHP-18) FOR TYPE 1 AND TYPE 2 DIABETES MELLITIS Brendan Mulhern 1 & Keith Meadows 2 1 Health Economics and Decision Science, University of Sheffield; 2 DHP Research and Consultancy Ltd There are now a range of diabetes specific patient reported outcome measures (PROMS) designed to assess health related quality of life. However there remains a lack in understanding as to what a PROM score represents and what is a meaningful change in score. We report a study estimating the minimally important difference (MID) for the Diabetes Health Profile (DHP-18) using anchor and distribution based techniques. The DHP-18 (Meadows et al., 2000): Consists of 18 items assessing HRQL in diabetes across three domains: Psychological Distress; Barriers to Activity; Disinhibited Eating. Is the diabetes-specific outcome measure selected for the UK Department of Health Patient Reported Outcome Measures Pilot for Long Term Conditions in Primary Care. For more info visit www.diabeteshealthprofile.com The Diabetes Health Profile Contact: Brendan Mulhern, Health Economics and Decision Science, University of Sheffield, Regent Court, Sheffield, S1 4DA; e-mail: b.mulhern@sheffield.ac.uk; website: www.shef.ac.uk/hedsb.mulhern@sheffield.ac.ukwww.shef.ac.uk/heds Reference: Meadows KA, Abrams C, Sandbaek A. (2000) Adaptation of the Diabetes Health Profile (DHP-1) for use with patients with Type 2 Diabetes mellitus: psychometric evaluation and cross-cultural comparison. Diab Med 2000; 17: 572-580. For further information see: Mulhern B, Meadows K. (2011). Estimating the MID of the Diabetes Health Profile for Type 1 and Type 2 Diabetes Mellitis. HEDS Discussion Paper, 11/08. Anchor based approach: 5 point global health change question used as anchor to indicate change in health status MID calculated as: Mean change on DHP dimensions (no change sample) – Mean change on DHP dimensions (small change sample) Distribution based approach: Three calculations used: 1. 0.2SD = 0.2 x standard deviation of baseline dimension score 2. 0.5SD = 0.5 x standard deviation of baseline dimension score 3. 1SEM: Calculating the MID Anchor based estimation sample: UK Longitudinal dataset of 1756 type 1 and type 2 patients Distribution based estimation sample: French Cross sectional dataset of 3387 type 1 and 2 patients used alongside anchor sample Sample Correlations The global health change anchor was more highly correlated with the type 1 patient sample (see below) MID estimations: Type 1 Type 2 Results Psychological distressBarriers to activityDisinhibited eating Baseline (n)Follow up (n)Baseline (n)Follow up (n)Baseline (n)Follow up (n) Type 10.183 (99)0.348* (98)0.232** (99)0.369* (99)0.052 (99)0.079(98) Type 20.146* (1158)0.185* (1130)0.127* (1155)0.202* (1129)0.026 (1156)0.111*(1130) Discussion We have estimated minimally important difference (MID) values for each of the three DHP-18 domains using both anchor and distribution based methods. Combining approaches has previously been used in a range of studies estimating the MID for measures of HRQL as there is no consensus about the best methodology to use For Type 1 Diabetes MID values within the estimated range for all 3 dimensions may be useful in determining those who display clinically meaningful change in HRQL For Type 2 Diabetes the anchor correlations are lower, and we recommend considering the full range of MID values, but applying more weight to the distribution based estimations This is the first attempt to calculate MID values for the DHP -18. The e estimations established in this study will help clinicians and researchers using the DHP-18 to identify clinical meaningful change in patient reported outcomes AnchorDistribution Type 1Type 2Type 1Type 2 Overall n (baseline)14316133744769 Overall n (follow up)100 (70.00)1184 (73.40)-- Age (m, sd)59.65 (15.65)66.19 (11.33)49.25 (14.14)65.32 (10.84) Gender Male55 (38.5)980 (60.9)187 (50.0)2693 (56.5) DHP-18 scores Psychological Distress27.30 (23.88)18.61 (20.69)30.59 (21.84)19.13 (19.42) Barriers to Activity34.63 (20.20)21.89 (19.20)32.43 (20.79)22.79 (18.38) Disinhibited Eating35.02 (22.44)36.02 (23.07)33.92 (23.07)34.32 (23.59)