Pulmonary Complications After Hip and Knee Arthroplasty in the United States, 2004–2014
Authors: Malcolm Tennison L. , Knezevic Nebojsa Nick , Zouki Carole C. , Tharian Antony R. 
Published: June 2019

BACKGROUND:
Pulmonary complications after total joint arthroplasty (TJA) are uncommon but have significant cost impact. Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are 2 of the 5 top procedures requiring inpatient stay within the United States. Subsequent pulmonary complications therefore may impose substantial cost burden for US health care. The purpose of this study was to describe the incidence, risk factors, and clinical implications of pulmonary complications (ie, pneumonia, respiratory failure, pulmonary embolism [PE], and aspiration) after TJA in the United States.

METHODS:
The National Inpatient Sample (NIS) was queried for all patients undergoing primary, elective THA and TKA between years 2004 and 2014. Pulmonary complications were defined as the occurrence of pneumonia, respiratory failure, PE, or aspiration after TJA. Demographic and clinical characteristics, inpatient cost, length of stay (LOS), and mortality were compared between patients with and without documented perioperative pulmonary complications. Given the stratified nature of the NIS database, estimates of incidence throughout the United States were made with application of trend weights to observed database frequencies. Analyses of estimated annual complication rates were made using χ2 tests.

RESULTS:
Between 2004 and 2014, an estimated 2,679,351 patients underwent elective primary THA. A total of 5,527,205 patients were estimated to have undergone elective primary TKA. THA 1.42% (95% CI, 1.37%–1.47%) and 1.71% (95% CI, 1.66%–1.76%) of TKA procedures were complicated by pneumonia, respiratory failure, PE, or aspiration. During this time, the incidence of perioperative pulmonary complications decreased from 1.57% (95% CI, 1.41%–1.73%) to 1.01% (95% CI, 0.92%–1.10%) after THA (P < .0001) and from 2.03% (95% CI, 1.88%–2.18%) to 1.33% (95% CI, 1.25%–1.42%) after TKA (P < .0001). The adjusted odds ratio (aOR) of experiencing a pulmonary complication was highest among patients with history of significant weight loss (aOR = 4.77; 99.9% CI, 3.97–5.73), fluid/electrolyte disorders (aOR = 3.33; 99.9% CI, 3.11–3.56), congestive heart failure (CHF; aOR = 3.32; 99.9% CI, 3.07–3.58), preexisting paralytic condition (aOR = 2.03; 99.9% CI, 1.57–2.61), and human immunodeficiency virus infection (aOR = 2.00; 99.9% CI, 1.06–3.78). Perioperative pulmonary complications were associated with increased LOS (THA = 3.03 days; 99.9% CI, 2.76–3.31; TKA = +2.72 days; 99.9% CI, 2.58–2.86), increased hospital costs (THA = +9163 US dollars; 99.9% CI, 8054–10,272; TKA = +7257 US dollars; 99.9% CI, 6650–7865), and increased mortality (THA: aOR = 121; 99.9% CI, 78–187; TKA: aOR = 150; 95% CI, 97–233).

CONCLUSIONS:
Despite a decline in overall incidence, perioperative pulmonary complications represent a significant potential source of perioperative morbidity and mortality. The current study highlights potential risk factors for pulmonary complications. Recognition of these factors may help to better stratify patients and mitigate risk of potential complications. This is particularly true of respiratory failure as it is associated with the high increases in resource utilization and mortality in this group.