Wednesday, March 12, 2008

Sex and The Single Girl Total Joint Arthroplasty

A fascinating Canadian study looked at the following question: Why do men have more than three times the rates of total knee arthroplasty than women? Here is the summary of the study:

Background: The underuse of total joint arthroplasty in appropriate candidates is more than 3 times greater among women than among men. When surveyed, physicians report that the patient's sex has no effect on their decision-making; however, what occurs in clinical practice may be different. The purpose of our study was to determine whether patients' sex affects physicians' decisions to refer a patient for, or to perform, total knee arthroplasty.

Methods: Seventy-one physicians (38 family physicians and 33 orthopedic surgeons) in Ontario performed blinded assessments of 2 standardized patients (1 man and 1 woman) with moderate knee osteoarthritis who differed only by sex. The standardized patients recorded the physicians' final recommendations about total knee arthroplasty. Four surgeons did not consent to the inclusion of their data. After detecting an overall main effect, we tested for an interaction with physician type (family physician v. orthopedic surgeon). We used a binary logistic regression analysis with a generalized estimating equation approach to assess the effect of patients' sex on physicians' recommendations for total knee arthroplasty.

Results: In total, 42% of physicians recommended total knee arthroplasty to the male but not the female standardized patient, and 8% of physicians recommended total knee arthroplasty to the female but not the male standardized patient (odds ratio [OR] 4.2, 95% confidence interval [CI] 2.4–7.3, p < 0.001; risk ratio [RR] 2.1, 95% CI 1.5–2.8, p < 0.001). The odds of an orthopedic surgeon recommending total knee arthroplasty to a male patient was 22 times (95% CI 6.4–76.0, p < 0.001) that for a female patient. The odds of a family physician recommending total knee arthroplasty to a male patient was 2 times (95% CI 1.04–4.71, p = 0.04) that for a female patient.

Interpretation: Physicians were more likely to recommend total knee arthroplasty to a male patient than to a female patient, suggesting that gender bias may contribute to the sex-based disparity in the rates of use of total knee arthroplasty.

Was that clear to you? If not, here's my attempt to summarize the idea in the study: The researchers selected two patients, one man and one woman, with similar levels of damage to their knees. These "standardized patients" were then trained to respond to all physician questions identically, including asking about knee surgery if it didn't crop up in the discussion. They were then sent to get consultations with all the physicians who agreed to participate in this study. Note that the physicians were not told the identity of the standardized patients or the day when they might come calling. Neither were they told that the topic of the study was related to the patient's gender.

Ok. Here we have two patients, all identical except for their gender, consulting with a large number of physicians about whether to get total joint arthroplasty or not. If physicians indeed don't take the patient's gender into account in their recommendations we'd expect the two standardized patients to get the same recommendation from each of the participating physician, right?

But that is not what happened. As the summary above mentions, the male patient was much more likely to get the recommendation than the female patient. What is especially worrying is that orthopedic surgeons, the specialists in this field, showed a far greater bias in that direction than family physicians who are generalists.

What does this all mean? It means that being a woman makes getting total joint arthroplasty more difficult, at least in the geographic area this study applies to, independently of any medical factors in this case.

Why would physicians practice this type of gender discrimination (for that is what the study found to exist)? That is not something the study can answer, but one intriguing possibility is this: Historically, the results from total joint arthroplasty have been worse for women, and this may be why the orthopedic surgeons were less likely to suggest it to the female patient. But here's where it gets very interesting: The reason the results have been worse for women, on average, is that women have gotten the surgery at more advanced stages of knee deterioration than men. Why? Could it be that physicians didn't recommend arthroplasty to women until the knee was very bad indeed?

See how all this could create a vicious cycle for the female patients? If the treatment doesn't seem to benefit women very much then physicians will not recommend it until there is literally nothing else left to recommend, and at that point the treatment will not work as well as it might have at an earlier stage. Enter the next round of the cycle...

Original link from Lance