Introduction:

Many studies track outcomes after procedures, such as posterior lumbar fusion (PLF), for only 30 days because of database limitations. However, adverse events may not have plateaued by this time. Thus, this study used an alternate database to evaluate the timing of adverse events for 90 days after PLF.

Methods:

Adult PLF patients were identified from the 2010 to 2020 Q2 M53Ortho PearlDiver administrative data set. Ninety-day rates of multiple adverse events were determined. The time of diagnosis for each event in the 90-day postoperative period was determined. Data were dichotomized by occurrence in days 0 to 30 and 31 to 90. Median, interquartile range, and middle 80% for the time of diagnosis were determined for each adverse event.

Results:

Of 51,915 patients undergoing PLF, 7,141 (13.8%) had an adverse event within 90 days of PLF. Of these, 5,174 (72.5%) experienced an event within 30 days and 2,544 (35.6%) after 30 days. For individual adverse outcomes studied, the percent that occurred 31 to 90 days after surgery ranged from 9% to 42%. The time of diagnosis (median; interquartile range; middle 80%) for each adverse event was as follows: transfusion (2 days; 2 to 5 days; 1 to 26 days), acute kidney injury (9; 2 to 29; 1 to 60), hematoma (9; 4 to 20; 3 to 39), cardiac event (11; 3 to 43; 1 to 71), pneumonia (12; 4 to 38; 2 to 68), venous thromboembolism (15; 6 to 33; 3 to 62), sepsis (19; 9 to 39; 4 to 63), surgical site infection (21; 14 to 34; 8 to 48), urinary tract infection (22; 8 to 49; 4 to 72), and wound dehiscence (27; 17 to 39; 9 to 54).

Discussion:

This study highlights the importance of looking past the 30-day mark for adverse events after PLF because approximately one-third of adverse events in this study were diagnosed 31 to 90 days after surgery. This can affect research studies, patient counseling about the incidence of specific adverse events, and the development of mechanisms for surveillance at key time points.