A recent study from Denmark by Lalmohamed et al. looked at stroke risk after total hip replacements. It is interesting as this is a severe disease that can have a major impact on the life after a total hip arthroplasty. Even if it’s a rare event, the rates are similar to other serious negative outcomes such as early infections (less than 1%), and therefore just as valid endpoint to study.
Lalmohamed et al. found that early on there seems to be a 4-5 times increase in risk, this decreases but remained elevated 6 weeks after surgery. They looked at both hemorrhagic and ischaemic stroke without noting any major difference, although the risk for hemorrhagic remained elevated slightly longer than ischaemic.
The study is a nation-wide registry study where they used a healthy matched cohort as control. While the setup was elegant I don’t understand why they only relied on ICD-codes for arthroplasties instead of co-operating with the Danish Hip Arthroplasty Register. Also apart from picking the obvious comorbidities as confounders it might have been useful to add a comorbidity score such as Charlson’s or Elixhauser’s.
In the statistics section I liked that they actually used a spline for the time since surgery factor. The plot is easy to interpret and makes intuitive sense, although confidence intervals should have been included. For confounder selection they use change-in-estimate method using univariate analyses. I guess it’s a nice method but not that commonly applied, and with their limited number of variables I’m not sure it was warranted for.
A nice and useful study that highlights a potentially serious complication after THR. We orthopaedic surgeons need to be vigilant, identify patients at risk, and make sure that risk factors are minimized prior to surgery.
A. Lalmohamed, P. Vestergaard, C. Cooper, A. de Boer, H. G. M. Leufkens, T. P. van Staa, and F. de Vries, “Timing of Stroke in Patients Undergoing Total Hip Replacement and Matched Controls A Nationwide Cohort Study,” Stroke, vol. 43, no. 12, pp. 3225–3229, Dec. 2012.