Brandle et al. (1) found that the occurrence of diabetes-related comorbidities in type 2 diabetic patients are associated with an increase in average annual medical cost.
To investigate the medical cost attributable to type 2 diabetes, we conducted a retrospective longitudinal cost-of-care study in a diabetologic center in Italy. A priori, we estimated to validly enroll 300 type 2 diabetic patients with at least 1 year of follow-up. To this aim, we randomly selected 315 type 2 diabetic patients from a base of ∼2,000 diabetic patients attending the diabetologic center of Portogruaro during the period from January 2001 to August 2002.
Cost included hospitalizations, visits, diagnostics, and pharmacological therapies and were quantified in the perspective of the National Health Service. We extracted clinical and demographic information from the electronic database and performed extensive chart review, including the comorbidities retinopathy, cardiopathy (coronary heart disease), vasculopathy (other than coronary heart disease), and nephropathy.
We analyzed the association between diabetes-related comorbidities and average annual medical costs using univariate and multiple linear regression analyses. In the linear regression analysis, cost was transformed using the square-root transformation to better fit a Gaussian distribution.
Sixteen type 2 diabetic patients were excluded because it was found that their follow-up period was <1 year; the main reasons were premature mortality and loss to follow-up. A total of 299 type 2 diabetic patients were considered for this analysis and followed-up for an average of 476 days, totaling 520 person-years of observation. Their mean (±SD) age was 68.6 ± 8.8 years, and 201 (67.2%) were men. The mean systolic blood pressure, diastolic blood pressure, total cholesterol, HDL cholesterol, HbA1c, and Hb levels were 152.5 ± 20.9 mmHg, 82.7 ± 10.0 mmHg, 195.5 ± 41.6 mg/dl, 50.2 ± 20.3 mg/dl, 7.1 ± 1.5%, and 13.9 ± 1.5 g/dl, respectively. The average annual cost of care was€,909.67 (i.e., $2,425 U.S.; exchange rate, 1 Euro = $1.27 U.S.); 52% of costs were attributable to drugs, 28% to hospitalizations, 11% to diagnostics, and 9% to visits.
A total of 101 (33.8%) type 2 diabetic patients were free of diabetes-related comorbidities, 117 (39.1%) had one complication, and 81 (27.1%) had two or more complications. The more frequent complication was vasculopathy, which affected 89 (29.8%) type 2 diabetic patients, followed by cardiopathy (79 [26.4%]), retinopathy (66 [22.1%]), and nephropathy (65 [21.7%]).
The annual medical costs increased with the number of complications from ,039.59 ($1,320 U.S.) to 1,808.17 ($2,296 U.S.) and to 3,141.21 ($3,989 U.S.) in type 2 diabetic patients with none, one, and two and more complications, respectively, with the association being statistically significant in both univariate (Kruskall-Wallis test, 73,035; P < 0.0001) and multiple linear regression analyses (R2 = 0.21; F test 82.5, P < 0.0001).
We could not assess the impact of dialysis on cost, since the care of type 2 diabetic patients developing end-stage renal disease is not controlled by the diabetologic center.
We did not consider the cost of supplies for self-monitoring of blood glucose, which is, at any rate, minimal (∼ 100 · patient−1 · year−1) and is not related to the type of complication.
Our study confirms the findings of Brandle et al. regarding the annual medical cost and its determinants in type 2 diabetic patients. Strategies aimed at preventing the onset of diabetes complications are likely to reduce medical costs in the long term, while improving patients’ health.