LONGITUDINAL GLUCOSE LOWERING TREATMENT PATTERNS IN METFORMIN MONOTHERAPY INITIATORS: IMPLICATIONS FROM A REAL-WORLD SETTING

Purpose: Clinical trials of intensive glucose lowering have raised questions about the potential harms of longitudinal treatment patterns that utilize complex drug combinations or have frequent changes.  In a real-world patient population, very little is known about what treatment patterns are used over time.        

Method: We created a national diabetes cohort using data from the Department of Veteran Affairs and Medicare.  Patients were included if they had ≥2 diagnostic codes conferring a positive diagnosis of type 2 diabetes, and age ≥40 years as of 1/1/2003.  We further limited the cohort to metformin monotherapy users (≥90 day supply of metformin dispensed during CY 2002 with no history of other pharmacologic intervention for diabetes).  Medication patterns were assessed from 1/1/2003 to 12/31/2011.  Patients were followed until leaving the cohort (death) or the end of the study.  Glucose-lowering drugs were categorized into 11 classes and dosing was ignored.  A patient was considered a user if they were dispensed ≥30 day supply at any point during the study period.  Drug episodes (discontinuation, restart, intensification and switching) and individual medication patterns were examined.

Result:

   Our cohort consisted of 76,216 veterans, who were majority male (98%), Caucasian (84%), and elderly (average age 66).  Thirty-five percent of the cohort died during the study period.  The average number of drugs prescribed per patient during the 9-year follow-up was 2.6 ± 1.4.  While most patients took a total of ≤2 different drugs over the 9 years, 11% took ≥5, with a very small percentage taking up to 9 different drugs.  Nearly 23% of the cohort maintained a metformin-only treatment pattern.  Within this group, 8% consistently used metformin, 83% had intermittent use (discontinuation and restart), and 9% discontinued metformin all together without switching to another drug.  The first drug episode of the remaining population was either a switch to another medication (15%), movement to dual-therapy (metformin plus another drug; 55%), or movement to triple-therapy and beyond (metformin plus ≥2 more drugs; 6%).  Sulfonylurea was the most common drug a patient was either switched to or intensified with. Overall, there were 27,760 unique longitudinal treatment patterns. 

Conclusion: There is extreme variability in medications that are prescribed in real clinical practice.  These patterns will be assessed in relation to diabetes-related complications.