Monday, December 11, 2006

Advanced directives and LMWH in cancer

Two from the latest American Journal of Medicine.

First is a look at ambulatory patients' knowledge of advanced directives. It comes from a survey of ~500 medicine outpatients in Buffalo, NY in 2004. A lot of data is presented that is probably of little interest to the average reader (including me). What was notable was 86% of the subjects said they didn't know what an 'advanced directive' was (although 86% of those subjects knew what a 'living will' was suggesting at least for this population 'advanced directive' is just not a familiar term, although the concept probably is). (This was also pre-Schiavo and one wonders if that made any difference.) The other notable finding was that over a third of patients did not want to discuss AD's with their provider, the vast majority of whom "didn't want to think about it." That says a lot, although it needs to be stressed that the survey included younger patients.

And from the supportive cancer front, there's a prospective, randomized, open-label trial comparing LMWH (tinzaparin) with coumadin for long-term anti-coagulation for cancer patients with venous thromboembolic (VTE) disease. This was a Canadian, multicenter study which looked at 200 patients with a DVT or PE--the primary outcome was the incidence of recurrent VTE disease. Most had solid tumors, and there was a relatively equal mix between metastatic and limited-stage disease (this was not a study of advanced cancer patients only). Patients received 3 months of LMWH or coumadin (coumadin patients initially received unfractionated heparin). After 3 months patients were taken off protocol (& it's unclear to me how many stayed on any anti-coagulation and if they did if they stayed on coumadin or LMWH or switched etc.)--patients were followed though for 12 months. They had data for 99% of patients randomized. Almost half the patients in each group had died by 12 months (no significant differences or even trends towards differences between the groups). Major bleeding and other complications were pretty equal between the groups. However--at both 6 and 12 months the LMWH group had less recurrent VTE (7% vs. 16% at 12 months, p=.044). This is further evidence that low molecular weight heparins might actually be more efficacious than coumadin for VTE in cancer patients. One can tell that the authors were disappointed that they didn't demonstrate a mortality benefit, although when 50% of your population dies during the study anyway you'd likely need a lot more than 200 patients in order to show a mortality benefit if it existed. That said, this was a missed opportunity for the researchers to look at health-related quality of life to see if it differed between the patients--and for me this is quite frustrating. How can you do such a solid, well-organized intervention study of a population in which 42% of the subjects have metastatic solid tumors and not look at quality of life as an outcome?

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