Table 1:

Medicare claims brain metastasis classification accuracy

Primary		Predicted	True	Sens	PPV	Spec	Kappa
	Algorithm: Synchronous
Lung	Overall	5,100	6,789	0.58	0.77	0.98	0.63 (0.62 – 0.64)
	Adenocarcinoma	2,103	2,806	0.59	0.79	0.98	0.63 (0.62 – 0.65)
	Carcinoma	403	571	0.57	0.80	0.98	0.62 (0.59 – 0.66)
	NSCLC	506	745	0.56	0.82	0.98	0.62 (0.58 – 0.65)
	Other	572	784	0.58	0.80	0.99	0.65 (0.62 – 0.68)
	SCLC	872	1,144	0.59	0.78	0.97	0.62 (0.60 – 0.65)
	Squamous	644	739	0.57	0.66	0.99	0.60 (0.56 – 0.63)
Breast	Overall	196	203	0.46	0.47	1.00	0.46 (0.40 – 0.53)
	Her2−/Hr+	103	86	0.41	0.34	1.00	0.37 (0.28 – 0.46)
	Her2+/ Hr(+/−)	27	31	0.48	0.56	1.00	0.51 (0.36 – 0.67)
	Other	38	50	0.44	0.58	1.00	0.50 (0.37 – 0.63)
	Triple (−)	28	36	0.58	0.75	1.00	0.65 (0.52 – 0.79)
Skin	Overall	152	230	0.55	0.83	1.00	0.66 (0.60 – 0.71)
	MMJN	*	*	0.43	0.60	1.00	0.50 (0.15 – 0.85)
	Nevi & Melanomas	134	206	0.54	0.83	1.00	0.65 (0.59 – 0.71)
	Other	13	*	0.71	0.92	1.00	0.79 (0.64 – 0.95)
	Algorithm: Lifetime
Lung	Overall	9,138	6,789	0.65	0.48	0.92	0.49 (0.48 – 0.50)
	Adenocarcinoma	3,630	2,806	0.65	0.50	0.91	0.50 (0.48 – 0.51)
	Carcinoma	575	571	0.63	0.62	0.95	0.57 (0.53 – 0.61)
	NSCLC	804	745	0.61	0.57	0.92	0.52 (0.49 – 0.55)
	Other	1,028	784	0.65	0.50	0.95	0.52 (0.49 – 0.55)
	SCLC	1,863	1,144	0.67	0.41	0.84	0.40 (0.38 – 0.43)
	Squamous	1,238	739	0.64	0.38	0.95	0.45 (0.42 – 0.48)
Breast	Overall	967	203	0.57	0.12	0.99	0.19 (0.16 – 0.22)
	Her2−/Hr+	430	86	0.53	0.11	0.99	0.18 (0.13 – 0.22)
	Her2+/ Hr(+/−)	181	31	0.68	0.12	0.97	0.19 (0.12 – 0.26)
	Other	144	50	0.54	0.19	0.99	0.27 (0.19 – 0.36)
	Triple (−)	212	36	0.58	0.10	0.96	0.16 (0.10 – 0.22)
Skin	Overall	658	230	0.66	0.23	0.98	0.33 (0.29 – 0.37)
	MMJN	114	*	0.71	0.04	0.99	0.08 (0.01 – 0.15)
	Nevi & Melanomas	498	206	0.65	0.27	0.97	0.36 (0.32 – 0.41)
	Other	46	*	0.82	0.30	0.95	0.42 (0.27 – 0.57)

For Medicare claims data algorithms identifying synchronous and lifetime brain metastases based on the presence of a diagnosis code for secondary cancer of the CNS and a procedure code indicating intracranial imaging within sixty days of the other, this table shows classification accuracy compared to a SEER SBM gold standard. The rows under “Algorithm: Synchronous” represent such an algorithm with the additional criteria that codes must have occurred within 60 days of primary cancer diagnosis, whereas “Algorithm: Lifetime” indicates that codes may have occurred at anytime in Medicare claims. “Sens” refers to sensitivity; “spec”, specificity; PPV, positive predictive value. An asterisk (“*”) represents values that are suppressed to avoid reporting data from 1 through 11 cases.