Date of Award

January 2021

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Jonathan N. Grauer

Abstract

Introduction: Preoperative laboratory studies are often obtained as part of the workup for common orthopedic procedures such as total hip arthroplasty (THA), total knee arthroplasty (TKA), and posterior lumbar surgeries. There has been increased focus on preoperative optimization and identifying and addressing preoperative risk factors for adverse outcomes. The implications of varying abnormally high, as well as low platelet counts, has yet to be assessed in large, multicenter patient populations.

Objectives:This thesis is a presentation of several related studies: (1) evaluate the cutoffs for normal vs. abnormal platelet counts for patients undergoing a variety of orthopedic procedures by utilizing postoperative complications data, (2) determine the safety of performing these procedures in patients with abnormal (low and high) platelet counts, and (3) to assess the correlation of abnormal platelet counts with readmission data using a national surgical database.

Methods:Patients who underwent elective primary THA, elective primary TKA, and elective posterior Lumbar surgeries were identified in the 2011-2015 National Surgical Quality Improvement Program (NSQIP) database. Risk of 30-day perioperative complications was calculated as a function of pre-operative platelet counts. Based on risk strata, patients were categorized into 3 groups: normal platelet counts, abnormally low platelet counts, and abnormally high platelet counts. Multivariate analyses were then performed to compare thirty-day postoperative complications, readmissions, operative time, and length of hospital stay between these populations.

Results:The studies presented identified 86,845 THA, 140,073 TKA, and 137,709 posterior lumbar surgery patients. Using the relative risk threshold of 1.5, platelet counts were divided into abnormal categories based on identified platelet count cutoffs.

Higher rates of any, major, and minor adverse events were associated with both the abnormally low and high platelet cohorts for the THA, TKA, and posterior lumbar patient cohorts. The abnormally low patient cohort was associated with a higher risk of readmissions for all the procedures studied, while the abnormally high patient cohort was associated with a higher risk of readmissions for THA, and TKA but not posterior lumbar surgeries.

Conclusion:Based on identified cutoffs for high and low platelet counts, abnormally high and low preoperative platelet counts were associated with adverse outcomes after elective posterior lumbar surgery, THA, and TKA. These findings facilitate risk stratification and suggest targeted consideration for patients with high, as well as low, preoperative platelet counts.

Comments

This thesis is restricted to Yale network users only. This thesis is permanently embargoed from public release.

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