July 2008

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Your doctor says you have six months to live. Should you believe him?

July 23, 2008 in Information | Permalink

Your doctor says you have six months to live. How accurate is this figure? Do you really have 4 moths to live? One year?

A paper by Alexander and Christakis (2008) analyzes physicians predictions of patient survival. The authors find that physicians systematically overestimate how long the patient will live. This bias is exacerbated when 1) the physician has a closer relationship with the patient or 2) the physician has to communicate their survival prediction directly to the patient.

In the paper, the authors collect data from a number of large hospices in Chicago. Before the patient was admitted to the hospice, the researchers asked the patient’s physician–usually the referring physician–to estimate how long the patient would survive. This was done using 3 measures:

(1) the point prediction is an answer to a question about the physicians’ best estimate of how long this patient has to live; (2) the communicated prediction is an answer to a question about what prognosis the doctor would communicate to the patient if the patient or the family insisted on receiving an estimate of survival; (3) the subjective distribution prediction is the physicians’ stated percent estimate that the patient would still be alive 7, 30, 90, 180 and 360 days after referral.

The closeness of the physicians to the patient is proxied with measures of the duration of their relationship, the frequency of their contact, and the date of their most recent contact.

Why would doctors overestimate survival? We assume predictions in the general case may be incorrect, but that estimates on average do not over- or underestimate survival probabilities. The lack of bias is due to the fact that we usually assume that individuals hope to reduce the mean-squared error of their prediction. The loss function, however, may not always be symmetric. One example of asymmetric loss functions comes from Varian’s 1974 paper, which investigates property value assessments in California. The paper showed that underestimate of property values cost the town money (in terms of the property tax received), but an overestimate could trigger the homeowner to file a lengthy and costly appeal process. Similarly, one would expect that doctors do not feel guilty giving the patient optimistic survival estimates, compared to the emotional stress which occurs when one has to communicate a pessimistic survival estimate to the patient.

The paper also finds evidence for two other types of biases: information bias and physician referential bias.

Information bias says that overestimates are more likely when the physician has less information about a disease. For this reason, we see that physicians have more accurate, less biased predictions for cancer patients. Why is this the case? Since cancer was the most likely reason why a person was admitted to a hospice, physicians have more experience caring for cancer patients. As the physician’s knowledge of a disease and frequency of dealings with patients who have a disease increase, the physician’s survival estimate becomes less biased.

Also, the physician’s physical observation (physician referential bias) will make predictions less accurate and more prone to overestimation. The authors claim that “[w]hen the patient is physically active, and able to function with little assistance on a daily basis, the physicians’ prognosis becomes more inaccurate and doctors inflate the estimates of their patients survival.”

  • Alexander M, Christakis NA (2008) “Bias and asymmetric loss in expert forecasts: A study of physician prognostic behavior with respect to patient survival” JHE, 27, pp. 1095-1108.
    • Varian, 1974 H.R. Varian, A Bayesian approach to real estate assessment. In: S.E. Fienberg and A. Zellner, Editors, Studies in Bayesian Econometrics and Statistics, North-Holland, Amsterdam (1974), pp. 195–208.

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    Americans have the best cancer survival rates

    July 22, 2008 in International Health Care Systems, Medical Studies | Permalink

    On Friday I reported that the U.S. scored poorly on the Commonwealth Fund’s National Scorecard. Those in favor of universal health care are probably rejoicing. “The U.S. system is dysfunctional beyond repair and we need universal health care!”

    Yesterday, the Economist reported on an article in The Lancet Oncology journal which found that the U.S. has the best five year survival probabilities for breast and prostate cancer. Score one for those against universal health care. “The American free market is always the best!”

    How can this be? How can we reconcile these two results?

    The Lancet Oncology article controls also for other covariates which are related to survival probabilities, but do not relate to the quality of health care. For instance, if Americans get cancer later in life than people from other countries this is taken into account since people who are older are more likely to die of almost all causes, including cancer. Further, if traffic mortalities or the homicide rate are higher in the U.S. than in other countries, this will likely decrease the probability a cancer patient survival for 5 years, but is unrelated to the quality of medical care. If Americans are more likely to be obese, this also will decrease their survival probabilities, but should not be an indictment against the health care system. For these reasons, the 5 year cancer survival probabilities are adjusted to take into account the age and death rates in the general population. After these effects are taken into account, the U.S. scores very well in terms of cancer survival.

    Of course cancer survival is only one of a myriad of ways of measuring the quality of the American health care system. Further, the U.S. spends the most money on healthcare (in total and per capita) compared to any other country. While the U.S. may (or may not) be the best, it is certainly the most expensive.

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    Roche to buy Genentech?

    July 21, 2008 in Current Events, Pharmaceuticals | Permalink

    In “Does Roche have Genentech’s Rx?“, NPR’s Marketplace reports on Roche’s bid to purchase all of Genentech, a firm that developed the three best-selling cancer drugs in the United States.

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    How San Diego is solving it’s traffic problem

    July 21, 2008 in Economics - General, Taxes | Permalink

    Last year, I wrote a blog post about how Los Angeles could fix its traffic problems.  Today, the San Diego Union Tribune reported that traffic has decreased between 3.3% and 9.1% during the week and between 5.2% and 11.9% on the weekends.  How has San Diego accomplished this?

    Higher gas prices are the reason.  A pleasant byproduct of higher gas prices are that less people will drive.  Of course, when less people drive, traffic decreases.

    As mentioned in the earlier post, instead of building more and more freeways, southern California should have implemented a gas tax or implement more toll on freeways.  Higher gas prices are in essence doing the same thing that a gas tax would.  Higher gas prices, however, end up in the pockets of oil companies whereas a gas tax could be used to create better public transportation infrastructure, thus making it easier not to use one’s car and thus further decreasing traffic.

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    Cochrane Review: The effect of capitation, fee-for-service (FFS) and mixed payment systems on primary care physician behavior

    July 21, 2008 in Academic Articles, Physician Compensation | Permalink

    Primary care physicians can be compensated in a number of ways. The most popular are capitation, fee-for-service, salary, or some mixture of the three. But how does the physician compensation method affect care levels? This is the question Gosden et al. (2000) try to answer in their Cochrane review. The authors search the literature for randomized trials or controlled before and after studies in order to see how changing physician compensation affects the quantity and quality of care.

    A summary of the 4 papers which met Gosden et al.’s criteria is below.

    Category Davidson 1992 Hickson 1987 Krasnik 1990 Hutchinson 1996
    Country US US Denmark Canada
    Type Randomized Trial Randomized Trial Before-and-After Before-and-After
    Payment i) age-adjusted capitation; ii) Medicaid FFS; iii) more lucrative FFS i) FFS; ii) Salary Control: Cap/FFS mix; Intervention: Capitation only, changes to Cap/FFS mix Before: FFS; After: mixed capitation, ambulatory care incentive
    Physicians Primary Care Providers (PCPs) Residents General Practitioners (GPs) GPs/Family Physicians
    Results Comparing FFS and capitation, there was no difference in the number of PCP visits. There was no difference in the number of patients attended The number of face-to-face and phone visits was higher in the control group than the intervention group. Hospital days decrease in all groups, but the change is similar across all payment types.

    		Controlling for covariates, there were 0.5-0.6 more visits for the capitation group compared to the Medicaid FFS. There were more ER visits for the salaried group compare to the FFS group. After the FFS was implemented in the intervention group, visits increased and converged to that of the control group.

    		The new, more lucrative FFS increase PCP visits by .8-.9 per patient compared to the Medicaid FFS. Salaried doctors have fewer well-child visits per enrollee After the FFS implementation [intervention group], the number of diagnostic and curative services order increased.

    		PCPs paid via capitation used fewer specialist and hospital resources After the FFS implementation [intervention group], the number referrals to specialists fell

    		Patients were less likely to reach recommended visit levels in capitation compared to FFS

    The original four articles:

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    Funding the Montgomery County margarita machine

    July 18, 2008 in Current Events, Public Policy | Permalink

    What happens to seized drug money? According to the Economist, in Montgomery County, Texas the sized drug money was used to fund the beer and liquor needs of the district attorney at their local county fair. The funds were also used to purchase a margarita machine.

    Looks like seized illegal drugs were used to fund legal drug use (alcohol).

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    U.S. Health Care scores poorly

    July 18, 2008 in International Health Care Systems, Quality | Permalink

    The Washington Post reports that U.S. Health Care [is] Still Ill. This conclusion comes from a report from the Commonwealth Fund titled Results from the National Scorecard on U.S. Health System Performance, 2008. Even though the U.S. still spends more money on medical care than any other nation, performance on the Scorecard has not improved between 2006 and 2008.

    Today, let’s look into some of these measures in detail.

    • Preventable Deaths/100,000 Population. This is calculated as the annual ratio of people below age 75 or below who die from diseases such as heart disease, stroke, bacterial infection, diabetes. These figures are age-adjusted so that if one country has a lot of old people, this does not count against them. This is a very good aggregate metric of how well the health care system is doing and it turns out that the U.S. is in last place.
    • Percent of adults (18+) who received all recommended screening and preventive care. Here we see pretty much no change between 2002 and 2005 (49% to 50%). However, using a metric such as all preventive care hides some improvements along the margin. For instance, let us assume that there are 5 key vaccines. If and half the population get all the vaccines and half of the population did not, then we would have a 50% score on this metric. On the other hand, if we had a huge improvement where the people who were not getting vaccinated now got 3 of the 5 vaccines, we would still be at the same 50% mark.
    • Quality of Care. We note that in most of the measurable quality metrics, performance increased. The number of diabetics with HbA1C<9% increased; the percent of people who received the proper care for heart attacks, heart failure and pneumonia increased as well. We see that more and more patients now receive written instructions after they are discharged from a hospital. Much of this improved quality may be coming from pay-for-performance interventions. As I have mentioned in earlier blog posts, P4P may improve the quality of care on measured dimensions, while reducing the quality of care in unmeasured areas.
    • Nursing Home hospitalizations. The percent of nursing home patients who were hospitalized in a year increased. This may be due to worse care, or an older–and thus generally sicker–population of adults being the ones who enter into nursing homes.
    • Off-Hours care: Although there was some improvement from 2005, Americans in 2007 were the least likely to be able to receive non-emergency care on nights, weekends, and holidays.
    • Access: The percent of people who are uninsured has risen greatly between 2000 and 2006. Further, 41% of adults have an outstanding medical debt of bill problem.
    • Coordination of care. When Americans have test done, they are the least likely to have these results available at the time of the next appointment. Among countries in the Commonwealth Report, only Canadians primary care physicians (PCPs) are less likely to use electronic medical records than American PCPs.

    Can these report cards help improve care? Yes an no. Of course, pointing out short-comings in the American system is the first step that is needed in order to improve care. The report, however, does not really explain why these short falls are occurring or how to fix them. Are adult preventive care levels low because physicians are not doing their job, or are patients avoiding needed checkups? The answer to this question will determine whether a physician-focused or public health-focused approach would work best. Similarly, we see that nursing home hospitalization are increasing. Why is this? Is this because of worse nursing home care or are the patients who enter into nursing homes sicker on average in more recent years? The the former is the culprit, what specific problems are leading to more hospitalizations and how can we fix them.

    I applaud the Commonwealth Fund for collecting this data. As they wisely state, “what receives attention gets improved.” However, more detail studies are needed if we really want to improve the quality, access and efficiency of health care in the 21st century.

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    CoR #56

    July 17, 2008 in Carnivals | Permalink

    The latest edition of the Cavalcade of Risk is hosted by Michael Cannon at the Cato@Liberty blog.  Some of my favorite posts include:

    • The Million Dollar Journey blog talks about the advent of Critical Illness (CI) insurance.  This is similar to the contingent claims insurance contract which economists have advocated–but has been difficult to apply in practice–for many years.
    • What happens when a physician operates on the wrong side of a patient?  How do you fix these quality control issues.  Paul Levy explains.

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    Should there be a mandated nurse/patient ratio in Nursing Home facilities?

    July 17, 2008 in Nurses, Nursing Homes, Public Policy | 2 comments

    A recent paper by Kitchener et al. (HSR 2008) investigates the actions of one nursing home chain to find how they maximized their profits. The authors find that Sun Healthcare Inc. employed three strategies to maximize shareholder value:

    1. rapid growth through debt-financed mergers;
    2. labor cost constraint through low nurse staffing levels; and
    3. a model of corporate governance that views sanctions for fraud and poor quality as a cost of business.

    Should the government impose a minimum nurse/patient ratio in order that quality care continues?

    Most libertarians abhor almost any form of regulation, but the case of the nursing homes may be an exception. The “customers” of nursing home care are elderly patients who–by definition–are in some way not able to take care of themselves. Thus, if the patient is treated poorly, it may be nearly impossible for them to change facilities or often it is even difficult for the elderly individual to communicate to their relatives that their care level is poor. The Kitchener paper found that one nursing home chain is sacrificing quality by using low nursing staffing level; should the government mandate a minimum nursing staffing level for nursing homes?

    I would argue that they should not. While nurses are of course one of the most–if not the most–important input which affects the quality of nursing home care, regulating inputs is not ideal. This regulation will likely stifle innovation. If new technologies are developed–such as a digital scale monitoring device mentioned in Akshay Kapur’s blog–it may be possible to substitute capital (technology) for labor (nurses) and achieve better medical care for lower costs.

    Should nursing homes be exempt from regulation? On this point, I believe that there should be some regulation. The government must continue to monitor nursing home quality and register complaints. Nursing homes with low quality scores or who abuse patients should not receive Medicare or Medicaid patients.

    It is important for the government to play a role in helping those who cannot help themselves; yet the government should not mandate how nursing homes should run their business, but instead insure that some minimum quality of care threshold is met.

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    Delaying the Medicare Paycut

    July 16, 2008 in Medicaid/Medicare, Physician Compensation | Permalink

    The controversy as to how much Medicare should pay doctors is continuing to brew (see N.Y. Times article).  Congress passed a law overriding a pay cut to Medicare doctors.  Although the president vetoed the bill, Congress garnered enough support to override the veto.

    Dr. Rich of The Covert Rationing Blog claims that the Medicare reimbursement mechanism “is so fundamentally ridiculous that it can only be understood by recognizing that it is a fairly typical bureaucratic attempt to covertly ration healthcare.”

    How would you enjoy having legislators determine your salary?

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