C-reactive protein levels for early detection of early postoperative complications after proximal femoral fracture surgery

We have studied the early C-reactive protein (CRP) kinetics after proximal femoral fracture (PFF) surgery and defined a chart of CRP threshold values beyond which early postoperative complications are likely.

We have prospectively followed up a 42-patient cohort for surgical treatment by osteosynthesis or hip arthroplasty, and CRP was dosed at admission, on day 1, day 3, day 5 and then twice weekly for 30 days at the same time as a platelet count control of low molecular weight heparins. Then, we identified postoperative complications (medical complications like infections other than the surgical site, thromboembolic complications, death and surgical complications like surgical site infections, dislocation, haematoma) and established the evolutive profile of CRP in a ‘complication’ group and a ‘no complication’ group. We developed a threshold value model for complications detection from our results and compared with Chapman’s 500/d formula (d being the postoperative day).

CRP in the ‘complication’ group (20 patients) is on average 19 points higher than the ‘no complication’ group (22 patients) (p = 0.007). Our model, which corresponds to the formula CRP(d) = e^{(4.71 − 0.06*d)}, is valid from day 1 to day 30 and has a threshold value of 105 mg/L at day 1. From day 5, the correlation between our chart and the 500/d chart is 0.84 (p < 10⁻⁵). Two successive CRP values strictly above our chart at a 48-h interval have a sensitivity of 65% and a specificity of 85% to detect a postoperative complication while only one CRP value above the chart has a sensitivity and a specificity of 48%.

Early postoperative CRP kinetics of PFF surgical patients can be modelled as a threshold value scale valid between day 1 and day 30. This can be an additional tool in the early detection of postoperative complications, if two CRP values are above the threshold values, without replacing the clinical examination, which remains the ‘gold standard’.

Prospective observational study.