Psychometric properties of a questionnaire to measure adherence to treatment in patients with type 1 diabetes mellitus.

AIM: To validate the psychometric properties of a questionnaire to measure adherence to treatment among people with type 1 diabetes mellitus and to evaluate its relationship with metabolic control.

DESIGN

A cross-sectional study of 167 adult people with type 1 diabetes mellitus recruited from the Endocrinology Service of University Hospital Doctor Peset (Spain).

METHODS

The validity of the content, construct and reliability of the instrument were evaluated and the results correlated with levels of glycosylated haemoglobin.

RESULTS

The questionnaire was composed of 25 items and 5 dimensions, with a score of 25-150 points and an internal consistency of 0.92, according to Cronbach's coefficient α. The content of validity ratio and the construct (exploratory functional analysis, Kaiser-Meyer-Olkin index and Barlett's spherical test) were adequate. We observed a significant correlation between glycosylated haemoglobin levels and treatment adherence.

CONCLUSION

The questionnaire to measure adherence to treatment in type 1 diabetes mellitus is consistent, reliable and valid, showing an excellent association with degree of metabolic control.