Table 4.

Self‐reported RA validation with Medicare claims, 2004‐2012

	Self‐Reported RA (n = 345)	Self‐Reported RA + RX (n = 161)	Self‐Reported RA + Doctor (n = 152)	Self‐Reported RA + RX + Doctor (n = 111)
CDC method: one or more RA claims
Sensitivity	0.23	0.18	0.18	0.15
Specificity	0.92	0.97	0.97	0.98
PPV	0.16	0.27	0.29	0.33
NPV	0.95	0.94	0.94	0.94
κ	0.13	0.17	0.18	0.17
CCW method: two or more RA claims
Sensitivity	0.40	0.43	0.31	0.26
Specificity	0.92	0.96	0.97	0.98
PPV	0.12	0.19	0.21	0.24
NPV	0.98	0.98	0.98	0.98
κ	0.15	0.20	0.23	0.23
Strict method: two or more RA claims, one from a rheumatologist
Sensitivity	0.55	0.45	0.55	0.45
Specificity	0.91	0.96	0.96	0.97
PPV	0.05	0.08	0.11	0.12
NPV	0.99	0.99	0.99	0.99
κ	0.07	0.12	0.23	0.18

CCW, Chronic Conditions Warehouse; CDC, Centers for Disease Control and Prevention; NPV, negative predictive value; PPV, positive predictive value; RA, rheumatoid arthritis.

RX = Self‐report that respondent is taking medication for arthritis. Doctor = Self‐report the respondent has seen a doctor in the past two years for arthritis. Sensitivity is the proportion of people with a Medicare history of RA reporting that they have RA. Specificity is the proportion of people without a Medicare history of RA of all respondents not reporting RA. The NPV is the proportion of respondents not reporting RA who have no Medicare history of RA. The CDC method is the CDC case definition of a single RA diagnosis. The CCW method is the CCW criteria of two RA diagnoses no greater than 2 years apart. The strict method is a minimum of two RA claims no more than 2 years apart, with a minimum of one claim from a rheumatologist.