Validity of the Center for Epidemiological Studies Depression scale in Type 2 diabetes.

OBJECTIVE

Depressive symptoms are common among people with Type 2 diabetes mellitus (T2DM). This study aimed to validate the 3-factor structure of the 14-item Center for Epidemiological Studies Depression (CES-D) scale proposed by Carleton et al. (2013) in a T2DM population.

METHODS

The CES-D was administered to consecutive patients with T2DM entering a rehabilitation program. Construct validity was assessed using confirmatory factor analysis. Subscale viability, differential item functioning, and associations with clinical characteristics were tested in bifactor models.

RESULTS

Among adults with T2DM (n=305, age 56.9±11.1, 44.9% male, duration of diabetes 7.8±7.9years, HbA1c 0.076±0.014%), the construct validity of Carleton's 3-factor solution (negative affective, positive affective and somatic symptoms) was confirmed, although negative affective and somatic symptoms were highly correlated (r=0.926). The CES-D items can be summed to arrive at a total score (ωH=0.869), but not subscale scores (ωS>0.7). Differential item functioning was not found based on age or body mass index (BMI), but Item 1 ("I was bothered by things that don't usually bother me") was inflated in women and Item 7 ("I felt that everything I did was an effort") was inflated in those with higher glycosylated haemoglobin (HbA1c). The general depression factor decreased with age (β=-0.247, p<0.001) and increased with BMI (β=0.102, p=0.041) but not HbA1c (β=0.065, p=0.461). Negative affective symptoms (β=0.743, p=0.001), but not other depressive symptoms, were higher in women.

CONCLUSIONS

The 14-item CES-D retained construct validity in adults with T2DM. Depressive symptoms were associated with younger age, female gender and BMI, but not with glycemic control.