Table 2. Comparison of Three definitions of OA using MEPS data.

Definition‡	Performance Measures (2008 - 2010)*						Annual Prevalence 2008 - 2011*			Symptomatic† 2008 - 2011*
	Sensitivity‡ (95% CI)		Specificity‡ (95% CI)		PPV‡ (95% CI)		sample n	estimate
								millions	(%)	%
Strict	34.6	(31.5 – 37.8)	97.5	(97.2 – 97.9)	33.5	(29.3 – 37.6)	4,838	14.4	(6.3)	92.3%
Expanded	73.8	(71.1 – 76.5)	90.5	(89.8 – 91.1)	26.3	(24.1 – 28.5)	19,035	51.4	(22.4)	89.1%
Probable	62.9	(59.8 – 65.9)	93.5	(93.0 – 94.0)	31.4	(28.8 – 34.1)	11,230	30.8	(13.4)	91.8%

^*Calculation of performance measures requires the use of restricted MEPS-MPC data; 2011 MPC data was not available when our access to these data was granted.

^†Assessed with the following question asked at the first and last assessment at each year “[Have/Has] [PERSON] had pain, aching, stiffness or swelling around a joint in the past 12 months?”.

^‡Strict, ICD-9-CM diagnosis 715; Expanded, ICD-9-CM diagnosis 715 , 716, or 719; Probable, ICD-9-CM 715 OR [716 or 719 AND prior non-RA arthritis diagnosis – assessed with a question asked of all adults “(Have/Has) (PERSON) ever been told by a doctor or other health professional that (PERSON) had arthritis?” and a follow-up question prompting the individual for the type of arthritis].

^§Sensitivity estimated on Subset A – participants with at least one MEPS-MPC medical counter diagnosis (n=24,022). Specificity and PPV estimated on Subset B – participants with MEPS-HC condition associated with at least one MEPS-MPC medical encounter diagnosis matched to a HC diagnosis (n=20,372).

OA, osteoarthritis; MEPS, Medical Expenditure Panel Survey; CI, Confidence Interval; PPV, Positive Predictive Value; ICD-9-CM, International Classification of Diseases Version 9 Clinical Modification; MPC, Medical Provider Component; HC, Household Component.