Prolonged Length of Stay Is Not an Acceptable Alternative to Coded Complications in Assessing Hospital Quality in Elective Joint Arthroplasty

We sought to determine if prolonged length of stay (pLOS) is an accurate measure of quality in total hip and knee arthroplasty (THA and TKA). Coded complications and pLOS for 5967 TKA and 4518 THA patients in our hospital discharged between 2009 and 2011 were analyzed. Of 727 patients with pLOS, only 170 also had a complication, yielding a sensitivity of 41.4% (95% CI: 36.7, 46.2) with a positive predictive value (PPV) of just 23.4% (95% CI: 20.3, 26.4). Specificity (94.5% [95% CI: 94.0, 94.9]) and negative predictive value (NPV) (97.5% [95% CI: 97.2, 97.8]) were high, due to the large number of patients without complications or pLOS. This suggests that risk-adjusted pLOS is an inadequate measure of patient safety in primary THA and TKA.