Article Figures & Data
Figures
- Figure 1.
Study design: Sampling, clinical event abstraction, and billing claims ascertainment. CV, cardiovascular; KT, kidney transplant; A, primary claims capture window; B, expanded window for claims ascertainment; C, adapted-Hebert algorithm for detection of diagnoses in claims.
Tables
- Table 1.
Definitions of cardiovascular diagnoses and procedures as recorded in the transplant center's clinical database
Parameter Clinical Criteria Cardiovascular diagnoses myocardial infarction “Definite” or “probable” events according to the Minnesota code electrocardiographic and biomarker criteria adopted by the American Heart Association for use in clinical research (30). congestive heart failure Guidelines incorporate into the diagnosis of heart failure clinical judgment on the basis of history and physical examination (31). Accordingly, indication of congestive heart failure within the database requires physician-reported diagnosis plus objective evidence of cardiac dysfunction (e.g., echocardiography or other forms of ventriculography, chest radiograph, and/or B-natriuretic peptide). atrial fibrillation Atrial fibrillation pattern on electrocardiography. stroke New focal neurologic deficit lasting ≥24 h, confirmed by brain imaging (computed tomography or magnetic resonance) transient ischemic attack New focal deficit that resolves within 24 h and was attributed to a central cause by the examining provider. venous thromboembolism Deep venous thrombosis was defined by clinical suspicion with confirmation by compression ultrasound of an upper or lower extremity. Pulmonary embolism was defined as positive or “high probability” findings by ventilation-perfusion lung scanning, spiral computed tomographic angiography of the chest, or pulmonary angiography. Procedures cardiac catheterization Coronary angiography performed for diagnostic or therapeutic purposes coronary artery bypass grafting Surgical revascularization of one or more coronary arteries amputation Surgical amputation of any portion of an upper or lower extremity peripheral arterial revascularization Angioplasty, atherectomy, or endarterectomy of one or more peripheral arteries or surgical arterial bypass - Table 2.
Billing claim codes used for identification of cardiovascular diagnoses and proceduresa
Parameter Billing Claim Codes Cardiovascular diagnoses myocardial infarction ICD-9-CM diagnosis: 410.x congestive heart failure ICD-9-CM diagnosis: 398.91, 422, 425, 428, 402.x1, 404.x1, 404.x3, V42.1 atrial fibrillation ICD-9-CM diagnosis: 427.31x stroke ICD-9-CM diagnosis: 430, 431, 432, 433.x1, 434.x1, 997.02 transient ischemic attack ICD-9-CM diagnosis: 435.x venous thromboembolism ICD-9-CM diagnosis: 453.4x, 453.8, 453.9, 415.11, 415.19 Procedures cardiac catheterization ICD-9-CM procedure: 37.21, 37.22, 37.23, 88.53 to 88.57 CPT: 93508, 93510, 93511, 93514, 93524, 93526, 93527, 93528, 93529, 93530, 93531 to 93533, 93539 to 93545, 93555, 93556, 93598 coronary artery bypass grafting ICD-9-CM procedure: 36.1x, 36.2 CPT: 33510 to 33523, 33533 to 33536 amputation ICD-9-CM procedure: 84.0x, 84.1x, 84.91; CPT: 24900, 24920, 25900, 25905, 25920, 25927, 27295, 27590, 27591, 27592, 27598, 27880, 27881, 27882, 27888, 27889, 28800, 28805 peripheral arterial revascularization: angioplasty, atherectomy, endarterectomy, or arterial bypass ICD-9-CM procedure: 39.25, 39.26, 39.29 CPT: 35331, 35341, 35351, 35355, 35361, 35363, 35371, 35372, 35381, 35450, 35452, 35454, 35456, 35459, 35470, 35471, 35472, 35473, 35474, 35480 to 35483, 35485, 35490 to 35493, 35495, 35521, 35531, 35533, 35541, 35546, 35548, 35549, 35551, 35556, 35558, 35563, 35565, 35566, 35571, 35583, 35585, 35587, 35621, 35623, 35646, 35647, 35651, 35654, 35656, 35661, 35663, 35665, 35666, 35671 ↵a “.x” indicates all fourth- and fifth-digit modifiers, unless otherwise noted. CPT, Common Procedural Terminology code; ICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification.
- Table 3.
Sensitivity of Medicare claims for detection of clinically recorded cardiovascular diagnoses and procedures, according to claims-based ascertainment algorithma
Event No. in Clinical Database (Reference) Single claims, ±30-d Window for Claims Ascertainment (Sensitivity % [95% CI]) Single Claims,Expanded Window for Claims Ascertainment (Sensitivity % [95% CI]) Adapted “Hebert Method” for Diagnoses (Sensitivity % [95% CI])c Total Medicare Eligibleb Part A Part B Part A or B Part A Part B Part A or B Diagnoses myocardial infarction 82 30 80.0% (78.0 to 92.0%) 83.3% (72.1 to 94.5%) 83.3% (72.1 to 94.5%) NC NC NC 80.0% (78.0 to 92.0%) congestive heart failure exacerbation 85 40 75.0% (63.7 to 86.3%) 85.0% (75.7 to 94.3%) 92.5% (85.6 to 99.4%) 77.5% (66.5 to 86.4%)e NC NC 92.5% (85.6 to 99.4%) atrial fibrillation 51 32 81.3% (67.7 to 94.8%) 84.4% (71.8 to 97.0%) 93.8% (85.4 to 100.0%) 90.6% (80.5 to 100.0%)f 87.5% (76.0 to 99.0%)e 96.9% (90.9 to 100.0%)e 93.8% (85.4 to 100.0%) stroke or transient ischemic attack 27 16 75.0% (53.8 to 96.2%) 81.3% (62.1 to 100.0%) 87.5% (71.3 to 100.0%) NC NC NC 87.5% (71.3 to 100.0%) venous thromboembolism 38 18 83.3% (66.1 to 100.0%) 77.8% (58.6 to 97.0%) 83.3% (66.1 to 100.0%) 88.9% (74.4 to 100.0%)f 88.9% (74.4 to 100.0%)f 94.4% (83.3 to 100.0%)f 83.3% (66.1 to 100.0%) Procedures cardiac catheterization 64 22 95.4% (66.7 to 100.0%) 90.9% (78.9 to 100.0%) 95.4% (66.7 to 100.0%) 100.0%d 95.4% (66.7 to 100.0%)e 100.0%d – coronary artery bypass grafting 19 4 100.0% 75.0% (32.6 to 100.0%) 100.0% NC NC NC – amputation 25 8 100.0% 87.5% (64.6 to 100.0%) 100.0% NC NC NC – peripheral revascularization 21 6 83.3% (53.5 to 100.0%) 100.0% 100.0% NC NC NC – ↵a CI, confidence interval.
↵b Claims sensitivity was computed using a reference standard of events recorded in the clinical database among Medicare-insured transplant recipients with sustained Medicare benefits at the time of the clinical event of interest.
↵c Diagnoses based on one Part A claim or two Part B claims submitted at least 1 d but no more than 365 d apart, in which case the latest claim date is defined as date of diagnosis; final diagnosis date was allowed to fall up to 30 d after the date in the clinical record. Medicare Part A represents institutional claims; Medicare Part B represents physician/suppliers.
Expanded claims-ascertainment windows were explored at
↵d ±45,
↵e ±60, and
↵f ±90 d. Results for the narrowest expanded window that maximized detection of events in the clinical record are reported. NC, no change in sensitivity with expanded window up to ±90 d.
- Table 4.
Statistical comparison of differences in the overall sensitivity of claims according to case definition and event type
Comparison Aggregate Sensitivity, p1_hat (x1/n1) Aggregate Sensitivity, p2<_hat (x2/n2) Z Statistica P Part A or B (1) versus Part A alone (2), all events, ±30-d ascertainment window 90.9% (160/176) 82.4% (145/176) 2.35 0.009b Part A or B (1) versusPart B alone (2), all events, ±30-d ascertainment window 90.9% (160/176) 84.6% (149/176) 1.79 0.037b Procedures (1) versus diagnoses (2), Part A or B claims, up to ±90-d ascertainment window 100% (40/40) 91.2% (124/136) 1.95 0.05c Claims ascertainment window up to ±90 d (1) versus ±30 d (2), using Part A or B claims all events 93.2% (164/176) 90.9% (160/176) 0.79 0.22b atrial fibrillation and venous thromboembolism 96.0% (48/50) 90.0% (45/50) 1.18 0.12b all other events 92.1% (116/126) 91.3% (115/126) 0.22 0.41b Adapted “Hebert method” (1) versus Part A or B claims (2) for diagnoses 88.2% (120/136) 89.0% (121/136) −0.19 0.43b ↵a Z = (p1_hat − p2_hat)/{[pp_hat(1 − pp_hat)]1/2 *[(1/n1) + (1/n2)]1/2 }, wherein the proportions compared are p1_hat = (x1/n1) and p2_hat = (x2/n2), and pp_hat= (x1+ x2/n1+ n2). Z >1.645 is significant at P < 0.05 when using a one-tailed test. Z >1.960 is significant at P < 0.05 when using a two-tailed test.
↵b Hypotheses with only one possible direction of difference were examined with a one-tailed test. Specifically, the addition of claims data for event ascertainment by inclusion of both Medicare parts or by an expanded capture window could increase sensitivity or produce no change but not reduce sensitivity; the requirement for additional confirmatory diagnosis claims could reduce or not alter sensitivity achieved with single claims but not increase sensitivity.
↵c The difference in sensitivity between procedures and diagnoses was examined with a more conservative two-tailed test.
Sensitivity of Medicare Billing Claims for Cardiovascular Diagnoses and Procedures among Kidney Transplant Recipients: A Comparison of Claims-based Case Definitions
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