Orthostatic intolerance following hip arthroplasty: incidence, risk factors and effect on length of stay: A prospective cohort study.

BACKGROUND: Early postoperative mobilisation is important for enhanced recovery, but can be hindered by orthostatic intolerance, characterised by dizziness, nausea, vomiting, feeling of heat, blurred vision and ultimately syncope. Although the incidence of orthostatic intolerance following total hip arthroplasty has been identified, few studies have yet investigated potential risk factors for developing orthostatic intolerance after hip arthroplasty. OBJECTIVES: The aim of this study was to assess the incidence of orthostatic intolerance on the first postoperative day after total hip arthroplasty, potential predisposing risk factors for developing orthostatic intolerance and its effect on length of stay. DESIGN: A prospective observational study. SETTING: Tertiary hospital, Auckland, New Zealand, May to September 2015. PATIENTS: One hundred and seventeen consecutive patients undergoing unilateral total hip arthroplasty. Patients were excluded if they had revision surgery. MAIN OUTCOME MEASURES: Incidence of orthostatic intolerance during mobilisation on the first postoperative day. Significant peri-operative risk factors for developing orthostatic intolerance were identified using logistic regression. Length of stay was compared between orthostatic intolerant and orthostatic tolerant patients using the Mann-Whitney U-test. RESULTS: On the first postoperative day, 22% of patients failed mobilisation due to orthostatic intolerance. Factors independently associated with orthostatic intolerance were female sex; OR (95% CI), 3.11 (1.01 to 9.57), postoperative use of gabapentin; OR 3.55 (1.24 to 10.15) and high peak pain levels (≥5/10) during mobilisation; OR 4.05 (1.30 to 12.61). Overall, 78% of patients were correctly identified. The model was more accurate at predicting those who would not get orthostatic intolerance (89% correct), compared with those who did have orthostatic intolerance (39% correct). Length of stay was longer in patients with orthostatic intolerance (P = 0.019). CONCLUSION: Orthostatic intolerance is common after total hip arthroplasty. Optimising pain control prior to mobilisation and limiting gabapentin use may modify the risk of developing postoperative orthostatic intolerance. Although personalised recovery pathways appear attractive, at present, the ability to predict at-risk individuals is still limited.