Psychometric evaluation of the Diabetes Symptom Checklist-Revised (DSC-R)--a measure of symptom distress.
OBJECTIVE
To assess the psychometric validity, reliability, responsiveness, and minimal important differences of the Diabetes Symptoms Checklist-Revised (DSC-R), a widely used patient-reported outcome measure of diabetes symptom distress.


METHODS
Psychometric validity of the DSC-R was assessed using blinded data from a large-scale trial of approximately 4000 type 2 diabetes patients. Confirmatory factorial analysis (CFA) and multitrait analysis were used to examine the construct validity of the structure of DSC-R. DSC-R internal consistency, discriminative validity, and responsiveness were also assessed. Distribution and anchor-based methods were used to estimate minimal important differences for DSC-R domains.


RESULTS
Mean age of the sample was 56 years, 42% were female, 88% were Caucasian. Patients had a mean body mass index (BMI) of 32.2 and mean glucose-fasting level of 151.7 md/dl. CFA and multitrait analysis indicated that the scoring of the DSC-R has acceptable construct validity. Item-scale correlations ranged from 0.44 to 0.78. Cronbach's alpha coefficients ranged from 0.69 to 0.87. At baseline, DSC-R scores were higher among patients with higher BMI scores (P < 0.0001), supporting the discriminative validity of the DSC-R. Minimal important difference estimates ranged from 0.39 to 0.60 points when using distribution methods and from 0.00 to 0.33 when estimated using anchor-based methods.


CONCLUSIONS
The DSC-R demonstrated excellent psychometric properties when tested in a large-scale diabetes clinical trial. Responsiveness and test-retest reliability of the DSC-R warrant further evaluation.
Arbuckle
Robert A
RA
Mapi Values, Adelphi Mill, Bollington, Macclesfield, Cheshire, UK. Rob.Arbuckle@mapivalues.com
Humphrey
Louise
L
Vardeva
Kawitha
K
Arondekar
Bhakti
B
Danten-Viala
Muriel
M
Scott
Jane A
JA
Snoek
Frank J
FJ
D000223:Adaptation, Psychological; D000704:Analysis of Variance; D001786:Blood Glucose; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000523:psychology*; D005260:Female; D014943:Global Health; D005905:Glyburide / Q000627:therapeutic use; D006442:Glycated Hemoglobin / Q000032:analysis; D006305:Health Status Indicators; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008297:Male; D008687:Metformin / Q000627:therapeutic use; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D000077154:Rosiglitazone; D012720:Severity of Illness Index; D018434:Sickness Impact Profile; D013315:Stress, Psychological; D011795:Surveys and Questionnaires / Q000592:standards*; D045162:Thiazolidinediones / Q000627:therapeutic use
D001786:Blood Glucose; D005905:Glyburide; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D008687:Metformin; D000077154:Rosiglitazone; D045162:Thiazolidinediones; C517652:hemoglobin A1c protein, human