Table 4.

Adjusted Odds Ratios for Differences in Categorical Disease Activity Measures Compared across Patients Seen in Practices with Nurse Practitioners or Physician Asssistants Versus Those with Rheumatologist Only

Variable	Primary analysis, per visit (OR, 95% CI) *	Secondary analysis, change between visits (OR, 95% CI)*	Secondary analysis, area under the curve (β coefficient) †
NP or PA (vs not)	0.32 (0.17–0.60)	0.98 (0.94–1.03)	−6.35 (p = 0.0055)
Disease activity category at baseline	...	...	9.85 (p < 0.001)
Age, per year	0.99 (0.98–1.02)	1.00 (0.99–1.00)	−0.005 (p = 0.95)
Female gender	2.24 (1.09–4.61)	0.98 (0.93–1.02)	0.34 (p = 0.89)
Duration of RA, per year	1.18 (0.87–1.61)	1.01 (0.99–1.03)	0.92 (p = 0.59)
Seropositive	1.26 (0.69–2.30)	1.02 (0.98–1.06)	1.08 (p = 0.59)
DMARD use, any	0.64 (0.43–0.95)	0.99 (0.94–1.03)	−2.85 (p = 0.20)

Notes: Categorical disease activity measures were remission (0), low disease activity (1), moderate disease activity (2), and high disease activity (3). The disease activity category at baseline was not entered into all analyses since it was part of the outcome. Abbreviations: NP, nurse practitioner; PA, physician assistant; RA, rheumatoid arthritis; DMARD, disease-modifying anti-rheumatic drug.

^*Odds ratio (OR) denotes the odds of a one level increase in disease activity, with odds ratios less than one denoting a reduced odds. They were calculated using a proportional odds model that accounted for the hierarchical clustering.

^†The β coefficients denote the area under the disease activity curve for the 24 months, with scores of 0–3 interpolated for each month. They were calculated in generalized linear models. Thus, the maximum value would equal 72. The patients seen in practices with mid level providers experienced a lower area under the curve (β = −6.35).