Physician preference motivates the use of anti-tumor necrosis factor therapy independent of clinical disease activity

Abstract

Objective: Physician preference has previously been shown to be an important determinant of prescription patterns, independent of patient-specific factors. We evaluated whether physician preference was important in the decision to select anti-tumor necrosis factor (anti-TNF) therapy rather than nonbiologic disease-modifying antirheumatic drugs (DMARDs) among rheumatoid arthritis (RA) patients initiating a new RA medication.

Methods: Using data from the Consortium of Rheumatology Researchers of North America, we identified RA patients who had never taken biologics initiating either anti-TNF therapy or a DMARD in 2001-2008. Physician preference for the use of anti-TNF agents was calculated using data from the preceding calendar year for each physician's other RA patients. Multivariable logistic regression with generalized estimating equations accounted for clustering of patients within the physician practice and evaluated the relationship between physician preference and receipt of anti-TNF therapy, controlling for patient-related factors and disease activity using the Clinical Disease Activity Index.

Results: We identified 1,532 RA patients initiating anti-TNF therapy or a DMARD. In models adjusting for tender and swollen joint counts and global disease activity, physician preference for the use of anti-TNF therapy was an independent predictor of receipt of these agents. Patients of physicians in the highest and middle tertiles of physician preference had a 2.50 (95% confidence interval [95% CI] 1.76-3.56) and 1.70 (95% CI 1.22-2.39) greater likelihood of receiving anti-TNF medications, respectively.

Conclusion: Physician preference is an important determinant of patients' receipt of anti-TNF therapy and may be useful to examine in future studies of RA treatment patterns, costs, and medication safety.

Figure 1

Adjusted* Relationship Between Physician Preference For Use of Anti-TNF Therapy (calculated using data from his/her other RA patients) and the Initiation of Anti-TNF Therapy (vs. non-biologic DMARDs) for the next RA patient, by Disease Activity** Note: the lowest tertile of physician preference for anti-TNF therapy is referent and corresponds to an Odds Ratio of 1.0 * adjusted for factors in the ‘administrative’ model from Table 1 ** RA disease activity was quantified using the Clinical Disease Activity Index (CDAI) and categorized as low (CDAI <= 10), moderate (CDAI > 10 to <= 22), or high (> 22)