Purpose: Real world drug utilization studies among biologic-treated Rheumatoid Arthritis (RA) patients may be confounded by differences in clinical, demographic, socioeconomic, or behavioral characteristics This study describes key demographic/clinical differences observed between patients treated with adalimumab (ADA); etanercept (ETA); and golimumab (GLM).
Method: The Optum Insight Clinformatics dataset was used to identify adult patients with ≥60 days supply of their assigned biologic medication, ≥ 2 claims with RA diagnoses (ICD-9: 714.xx) and ≥24 months of continuous medical and pharmacy eligibility. Assignment to an index group ( ADA, ETA or GLM) was based upon the most recent biologic used during the enrollment period (1/1/ 2009 to 3/31/2011). Demographic and clinical characteristics were summarized for the year prior to the index date using descriptive statistics.
Result: A total of 2,222 ADA; 3,168 ETA, and 347 GLM patients met inclusion criteria. The GLM group was younger than the ETA group (p < .0005;); and had more female patients, a higher proportion of patients with cerebrovascular disease ,osteoarthritis,hypertension depression, chronic pain, (p's < .05) and a higher proportion with prior biologic medication use (p's < .0001) compared to both ADA and ETA groups; see TABLE. Likewise, in the pre-index year, total RA-specific and non-RA health care costs were higher for GLM patients compared to the other groups. (p's < .001); see TABLE.
TABLE: Pre-Index Demographic and Clinical Characteristics and Related Costs | ||||
Variable | ADA | ETA | GLM | omnibus test p value |
n = 2222 | n = 3168 | n = 347 | ||
Characteristics | % | % | % |
|
Female | 75.2% | 74.6% | 81.3% | 0.023 |
< age 65 years | 91.7% | 89.4% | 93.4% | 0.003 |
Prior Biologic Use | 15.4% | 8.0% | 60.5% | 0.000 |
Cerebrovascular Disease | 2.9% | 2.9% | 5.5% | 0.029 |
Osteoarthritis | 55.7% | 52.9% | 64.8% | 0.000 |
Hypertension | 35.5% | 34.4% | 42.1% | 0.017 |
Depression | 10.3% | 8.8% | 15.3% | 0.000 |
Chronic Pain | 4.0% | 3.6% | 9.2% | 0.000 |
Costs | Mean | Mean | Mean |
|
RA-specific Costs | $14,631 | $14,020 | $18,691 | 0.000 |
Non RA-specific Costs | $16,962 | $16,823 | $25,241 | 0.000 |
Conclusion: The GLM group was younger, sicker, and incurred greater total health care costs compared to the ADA and ETA groups. These findings suggest that direct comparison of patients using these products is confounded with pre-index disease severity and other indicators. Research studies adjusting for patient differences should be employed when studying overall drug utilization patterns or healthcare costs.