In the current climate of increasing financial pressures and reducing bed numbers, a predictor of length of stay (LOS) may have a bearing on hospital finances. Independent sector treatment centres may also skew the ASA grade and co-morbidity of the patient group treated in a hospital setting. We performed a study of 100 consecutive patients undergoing Total hip or knee arthroplasty between April and September 2006.

Median age was 71 years (35 – 88) with 75% of patients having significant (cardiac, renal or respiratory) pre-existing medical conditions (24% with 3 or more conditions). Average ASA grade was 2 (15% grade 3) and average BMI was 30. A significant reduction in LOS from 8.47 to 5.87 days was seen in under 70 year olds when compared with those over 70 years (p = 0.0004), having 3 or more co-morbidities (compared with 2 or less) increased average LOS from 6.61 days to 9.3 days (p = 0.002), ASA grade of 3 increased LOS to 9.56 days from 6.27 and 6.87 for grade 1 and 2 respectively (p = 0.014) and living alone (compared with cohabiting) increased LOS from 6.55 days to 9.19 days (p = 0.0017). However no statistical significance was seen for BMI with an average of 7.19 days for < 30 and 7.37 days for patients with BMI of 30 or above (p = 0.82)

Regardless of this patient group being elderly and obese with significant co-morbidity, an acceptable outcome was seen, with 70% of patients discharged within 7 days and only 4% staying > 14 days. Although BMI did not predict outcome, number of co-morbidities, ASA, age greater than 70 years and living alone all demonstrated a significant increase in LOS. Increased resources in this at risk group within a pre-admission setting could reduce length of hospital stay.