Friday, January 9, 2009
Journal of the American College of Cardiology has a paper looking at changing treatment preferences for survival after a hospitalization for heart failure. The data come from a prospective trial of hospitalized heart failure patients (N=404, mean age in upper 50s) in which treatment preferences for quality (actually health status) vs. quantity of life were measured using 'time-trade off' methods. Their description of TTO is below - basically ranged from scores from 0 (completely values quality of quantity) to 1 (quantity over quality):
The TTO instrument was administered verbally by the study nurse at 1, 2, 3, and 6 months. Whenever possible, this instrument and written questions were administered in the absence of family. After a scripted introduction, the initial question was “Would you prefer living 2 years in your current state of health or living 1 day in excellent health?” An answer of 1 day, equated to a utility of 1/730 (0), would end the script. An answer of 2 years would be followed by the next choice, between living “2 years in your current state of health or living 1 year 11 months in excellent health.” After sequential choices, the number of months (up to 24 months) in excellent health that the respondent considered to be equivalent in value to 24 months of survival in current health was recorded, and this ratio was the utility (between 0 and 1). The number of months at the indifference point subtracted from 24 yielded the number of months of survival time that the patient would be willing to trade.Complex, yes I know, and there's a good (and historically minded) discussion of this method given in an excellent accompanying editorial.
They found a distinct bi-modal distribution of answers: 40% of patients more or less said they'd trade no time, 28% said they'd trade nearly 2 years of time to be in excellent health, with a smattering of the rest in between. Demographics including age and ethnicity didn't predict which group patients belonged to, although functional status did (with those willing to trade 2 years having the worst 6 minute walk test results - 60 meters [which is terrible]). Other interesting findings:
- Preferences didn't change much over time (on average just by 4% using the TTO 'scale). However those that did change substantially (a minority of patients had relatively large changes), most of those changed with preferences for increased survival time.
- Changing preferences for increased survival time were associated with improved functional status/decreasing symptoms. (Most patients had improved functional status and decreasing symptoms anyway - as one would expect given that at baseline these patients were hospitalized with heart failure - however those whose preferences changed the most had a more pronounced improvement in symptoms than the others).
- Preferring quality over time was associated with earlier death: 30% of the patients who died by 180 days preferred quality over time, compared to only 6% of those who survived 180 days. Given that these patients were sicker (as mentioned by functional status) at baseline and that this data come from a trial of using pulmonary artery catheters in CHF management (ie these were patients willing to receive PA catheters and so were likely also receiving/willing to receive 'aggressive' care) these preferences were likely markers of poor prognosis, as opposed to causes of it.
L STEVENSON, A HELLKAMP, C LEIER, G SOPKO, T KOELLING, J WARNICA, W ABRAHAM, E KASPER, J ROGERS, R CALIFF (2008). Changing Preferences for Survival After Hospitalization With Advanced Heart Failure Journal of the American College of Cardiology, 52 (21), 1702-1708 DOI: 10.1016/j.jacc.2008.08.028
Thanks to Dr. Bob Arnold for this.