Cost sharing, adherence, and health outcomes in patients with diabetes

OBJECTIVES

To assess the relationship between cost sharing and adherence to antidiabetic medications in patients with type 2 diabetes and to examine the relationship between medication adherence and outcomes, including complication rates, medical service utilization, and workplace productivity measures.

STUDY DESIGN

A retrospective, cross-sectional study analyzing the healthcare experience of patients with type 2 diabetes on oral antidiabetic medication (OAD) with or without insulin (n = 96,734) and patients on OAD only (n = 55,356) with employer-sponsored insurance in the 2003-2006 MarketScan Database.

METHODS

Using a 2-stage residual inclusion model, the first stage estimated the effects of cost sharing on adherence to antidiabetic medications in an 18-month time frame (January 2003 through June 2004). Adherence was determined from the percentage of days covered. The second stage estimated the effects of adherence on complication rates (eg, retinopathy, neuropathy, peripheral vascular disease), medical service utilization rates, and measures of productivity (absence days and short-term disability days) in the subsequent 2 years (July 2004 through June 2006).

RESULTS

A $10 increase in the patient cost-sharing index resulted in a 5.4% reduction in adherence to antidiabetic medications for patients on OAD only and a 6.2% reduction in adherence for patients on OAD with or without insulin. Adherence was associated with lower rates of complications (eg, amputation/ulcers, retinopathy) and also was associated with fewer emergency department visits and short-term disability days.

CONCLUSIONS

Medical plans, employers, and policy makers should consider implementing interventions targeted to improve antidiabetic medication adherence, which may translate to better outcomes.

Zimelidine and amitriptyline in the treatment of depressive illness in general practice

Depressive patients seen at hospital clinics are likely to be unrepresentative in terms of treatment response. In this study patients were always seen at their general practitioners' surgeries for assessment by specialists after selection as being in need of antidepressant treatment. The Research Diagnostic Criteria for major or minor depressive illness and a Hamilton Depression (Ham-D) score of at least 10 were required for inclusion, using the Present State Examination as a basis for interview. Patients were seen at weekly intervals, alternatively by practitioner and assessor for further Ham-D ratings, completion of the Kellner Sheffield Self-Rating test (KSSRT), event record and side effect checklist. Patients were randomly and blindly allocated to either zimelidine or amitriptyline dispensed identically at dosages of 100 mg and 75 mg at night, rising to 200 mg and 150 mg after two weeks. At four weeks there was no significant difference between the improvement found with zimelidine and amitriptyline or either the Ham-D or the KSSRT. Amitriptyline patients tended to gain and zimelidine patients to lose weight; difference significant. Other amitriptyline side effects were not found in those taking zimelidine, the latter tending to suffer diarrhoea. Preliminary analysis shows no relationship between clinical response and plasma level of either compound.