TABLE 1.

Event Level Analysis of Training Data Set. Comparison of the Performance of Different Medicare Stroke Definition Algorithms vs. Physician Adjudicated WHI Stroke Events Using a 7-day Match Window.^*

	Total	WHI Yes CMS Yes	WHI No CMS Yes	WHI Yes CMS No	WHI No CMS No	SN	SP	PPV	NPV	Kappa
Stroke (any diagnosis code; definition 1)
All	31399	478	318	104	30499	82.1	99.0	60.1	99.7	0.69
WHI Hospitalization reported ¹	31212	478	136	99	30499	82.8	99.6	77.9	99.7	0.80
WHI Hospitalization adjudicated ²	31115	478	79	99	30499	82.8	99.7	85.8	99.7	0.84
Stroke (principal diagnosis; definition 2)
All	31448	429	237	153	30629	73.7	99.2	64.4	99.5	0.68
WHI Hospitalization reported ¹	31311	429	105	148	30629	74.4	99.7	80.3	99.5	0.77
WHI Hospitalization adjudicated ²	31277	429	71	148	30629	74.4	99.8	85.8	99.5	0.79
Hemorrhagic Stroke (definition 3)
All	31323	82	49	27	31165	75.2	99.8	62.6	99.9	0.68
WHI Hospitalization reported ¹	31296	82	23	26	31165	75.9	99.9	78.1	99.9	0.77
WHI Hospitalization adjudicated ²	31281	82	8	26	31165	75.9	>99.9	91.1	99.9	0.83
Ischemic Stroke (definition 4)
All	31379	369	296	84	30630	81.5	99.0	55.5	99.7	0.65
WHI Hospitalization reported ¹	31218	369	139	80	30630	82.2	99.5	72.6	99.7	0.77
WHI Hospitalization adjudicated ²	31175	369	96	80	30630	82.2	99.7	79.4	99.7	0.80

Abbreviations: CMS, Centers for Medicare & Medicaid Services data, i.e., Medicare data; NPV, negative predictive value; PPV, positive predictive value; SN, Sensitivity; SP, Specificity; WHI, Women’s Health Initiative data.

Excludes strokes in the outpatient setting. Also, excludes events for which no WHI hospitalization was reported by the participant or a proxy with admission date within +/− 7 days of the Medicare hospitalization.

Excludes events for which no medical records were received due to administrative reasons (e.g., no record release or no documents) or when reasons reported for hospitalization did not trigger adjudication (e.g. bunionectomy).

Analysis based on a nationwide dataset.