Aims. Smoking is associated with post-operative complications but smokers often under-report the amount they smoke. Our objective was to determine whether a urine dipstick test could be used as a substitute for quantitative cotinine assays to determine smoking status in patients. Patients and Methods. Between September 2013 and July 2014 we conducted a prospective cohort study in which 127 consecutive patients undergoing a planned foot and ankle arthrodesis or osteotomy were included. Patients self-reported their smoking status and were classified as: ‘never smoked’ (61 patients), ‘ex-smoker’ (46 patients), or ‘current smoker’ (20 patients). Urine samples were analysed with cotinine assays and cotinine dipstick tests. Results. There was a high degree of concordance between dipstick and assay results (Kappa coefficient = 0.842, p < 0.001). Compared with the quantitative assay, the dipstick had a sensitivity of 88.9% and a specificity of 97.3%. Patients claiming to have stopped smoking just before surgery had the highest rate of disagreement between reported smoking status and urine testing. Conclusion. Urine cotinine dipstick testing is cheap, fast, reliable, and easy to use. It may be used in place of a quantitative assay as a screening tool for detecting patients who may be smoking. A positive test may be used as a trigger for further assessment and counselling. Cite this article: Bone Joint J 2016;98-B:1418–24

Introduction. Pre-operative urine screening is accepted practice during pre-operative assessment in elective orthopaedic practice. There is no evidence surrounding the benefits, effects or clinical outcomes of such a practice. Methods. A series of 558 patients undergoing elective admission were recruited during pre-assessment for surgery and were screened for UTIs according to a pre-existing trust protocol. All patients had their urine dipstick tested and positive samples were sent for culture and microscopy. Patients with a positive urine culture were treated prior to surgery and were admitted to the elective centre where strict infection control methods were implemented. The patients were followed up after their surgery and divided into three clinical groups: uneventful surgery; Suspected wound infection; Confirmed wound infection. Results. 85% of dipsticks tested were positive, while only 7% of the urine samples were culture positive. Over 36% of patients with a pre-operative urinary tract infection showed some form of post-operative delayed wound healing or confirmed infection, versus 16% in the other sub-group, giving a relative risk of wound complications of 2:1. There was also an increase in confirmed infection in oozing wounds; 53% positive wound swabs versus 37% in those without a cultured urinary tract infection. A chi-squared analysis yielded a value of 6.07, giving a p value <0.02. There is therefore a statistically significant correlation between a positive urine culture and poor surgical outcome. Conclusion. Pre-operative urine screening and culture has a demonstrable correlation with post-operative surgical outcome. In the light of this study pre-operative urine culture should be mandatory for all pre-operative orthopaedic patients. It should be recognised that patients who present to pre-admission with a UTI are a high risk subgroup for wound infection post-operatively and this should be taken into account when consenting patients for surgery