Background

Adherence to medication, physical activity (PA) and diet in diabetes mellitus (DM) patients is crucial for its good management, avoiding acute and chronic complications. There are several risk factors associated with non-adherence, including cognitive impairment, depression and anxiety. Nevertheless, studies on therapeutic adherence in older patients with DM are scarce. In this context, the present study aimed to analyze whether adherence to medication, PA and diet are associated with cognitive impairment, anxiety and depression. It also aimed to identity predictors of medication non-adherence.

Methods

A cross-sectional study of older patients (≥ 65 years old) with DM was carried out in the Outpatient Department of Internal Medicine Service of CHUSJ-Porto, Portugal. Those unable to communicate were excluded. Cognition (mini-mental state examination), anxiety and depression (hospital anxiety and depression scale) were assessed. Adherence to medication, PA and diet was measured, based on self-reporting patient/family, questionnaires, physician clinical opinion, hemoglobin test and pharmacy records. Patient groups were compared, using the Mann-Whitney or the Kruskal-Wallis test for continuous variables and the Chi-square test for paired categorical variables (significance level of 0.05). The odds ratio (OR) was calculated to identify independent predictors of non-adherence to medication.

Results

The final sample (n= 94) had a mean age of 75.2 years (standard deviation: 6.7) and mostly were female (53.2%), married (63.8%) and with a low education level (61.7%). Also, 22.3% with cognitive impairment, 16% with depression and 23.4% with anxiety were found. Patients non-adherent to medication had higher depression (P= 0.048) and anxiety (P= 0.010), compared to adherents/partial adherents. Patients non-adherent to PA showed higher anxiety (P= 0.035) and depression (P= 0.004), compared to adherents. Non-adherents to PA had more cognitive impairment than adherents (26.3% vs. 0%; P= 0.034). Patients who had insulin prescribed presented a higher risk of non-adherence to medication (OR: 4.041, 95% confidence interval (CI): 1.404-11.628; P= 0.010). Also, the risk of non-adherence to medication is higher by an increase of one unit in anxiety (OR: 1.252, 95% CI: 1.046-1.499; P= 0.014).

Conclusions

Higher anxiety and depression were associated with non-adherence to medication and to PA. Insulin prescribed and high anxiety scores were predictors of medication non-adherence. This study appears to contribute to the knowledge about the influence of cognitive and psychological factors in therapeutic adherence in these older diabetic patients.