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April 18, 2011

Driving Superior Clinical Outcomes: What is the Secret Sauce?


2 Comments to “Driving Superior Clinical Outcomes: What is the Secret Sauce?”

  1. Richard J. Glassock, MD said,

    April 20, 2011 @ 1:52 pm

    BLOG on Chronic Kidney Disease and ESRD

    Dear Bloggers:

    With Allen’s encouragement, I am adding to the blogo-sphere a brief essay (really and opinion-piece) on a topic that has occupied my thoughts for several years and now I have an opportunity to share it with some friends and colleagues for their reactions.

    I would like to call for a “moratorium” on the use of the term “epidemic” in the context of the epidemiology of CKD and ESRD.

    An “epidemic” can be defined as an outbreak of a disease that spreads more quickly and more extensively among a group of people than would normally be expected (MSN-Encarta)

    A careful examination of the literature data shows that for most industrialized nations the prevalence (and incidence) of CKD Stages 1-4 is stable (but this depends on the formulas used for calculating eGFR and the fraction of the population who are elderly). To be sure, CKD is endemic ( a disease occurring within a particular area- MSN Encarta) in many countries- but the actual percentage of the population that is afflicted with CKD Stage 1-4 at any given time is hotly debated. My views on this are well known– I estimate that about 4-5% instead of 11-13% of the population of the USA has “real” CKD that can, have adverse consequences on survival or the quality of life , independently of other conventional risk factors such as hypertension or diabetes, but this depends on the definitions used to diagnose CKD. These current definitions I believe greatly inflate the diagnosis of CKD, most notably in the elderly.

    The epidemiology of treated ESRD (treated CKD Stage 5) is another matter. The incidence of newly treated ESRD has plateaued in most industrialized nations of the world, whereas the prevalence continues to grow in these same countries. The steady rise in the prevalence rates for dialysis-treated ESRD can largely be accounted for by improved survival on treatment and by patients returning to dialysis after a failed renal transplant. It follows that once a maximum obtainable survival (lowest achievable mortality rates) on dialysis is attained in these countries the prevalence rate of dialysis-treated ESRD will inevitably stabilize or even diminish, unless, of course, the incidence rate of treated ESRD somehow returns to pre-1995 levels (an unlikely prospect in my view). .Developing, resource-poor, countries have experienced a rise in the incidence of dialysis-treated ESRD mostly because of improved access to care. In the USA, some of the “steam” that drove increased dialysis treatment rates between 1996 and 2006, namely “early start” of treatment (when the eGFR is >10ml/min/1.73m2M), is likely to dissipate as clinician recognize that such eGFR driven “early start” offers no real survival advantage for patients with ESRD and may even be harmful.

    In sum, the prevalence of dialysis-treated ESRD resembles the epidemiology of cancer therapy. Rising access to effective cancer care and improved success in its control (but by and large not long term cure) has led to a burgeoning of the prevalence of cancer survivors (an “epidemic” of cancer) despite the relatively stable incidence of newly discovered cancer in the community as a whole.

    If there is an “epidemic” of CKD, it is confined largely to dialysis-treated ESRD and it is iatrogenic in nature. (e.g. “early start, improved access and some (albeit small) lowering of mortality on treatment Thus, it is a manifestation of “success” rather than a “failure” of public health (especially in industrialized countries willing to expend societal resources on a limited number of patients with a chronic disease).

    This does not mean at all that attempts to reduce the incidence of CKD Stages 1-4 and its progression to ESRD are misguided. Nor can we predict what may happen in the future, especially consequent to the projected increase in the prevalence of diagnosed Type 2 DM globally and the steady aging of the population (gains in estimated longevity from birth).

    However, we do not need hyperbole (such as the fear engendered by the word “epidemic”) to justify the urgent need to find ways to reduce the burden of many forms of CKD and its risk for death or disability.

    Some believe that a large reservoir of undetected and modifiable CKD exists in the community at large. This may be true, and it would likely be more relevant for underdeveloped countries than the major industrialized nations. Some observers reason that this “hidden” CKD should be a sufficient rationale to embark on large-scale efforts at screening for CKD. Yet, the evidence that such efforts have made a beneficial impact on patient-centered outcomes (such as death or disability), after accounting for biases (such as lead-time bias), is scanty. We also do not know the values for false and true positives of screening procedures for early identification of CKD (in terms of ultimate development of treated ESRD) nor do we clearly understand the overall cost- effectiveness of universal or targeted screening for CKD. Such screening efforts undoubtedly do increase public awareness—but where is the evidence for a real benefit and how can these screening efforts be optimized to yield a meaningful change in patient-centered outcomes? Is screening for eGFR and albuminuria any better (or worse) than screening for elevated blood pressure or diabetes? In addition, wide-spread de facto screening for CKD by routine reporting of eGFR whenever a serum creatinine is measured and translation of the eGFR value into a Stage of CKD results in an great increase in often unnecessary referrals from Primary Care Physicians to Nephrologists exacerbating an already burdened cadre of physicians. But does this de facto screening translate into better outcomes? Preliminary evidence shows that it does not. We need better guidelines for such referrals and some harder evidence that they really do make a difference.

    In my opinion, we need to pause and reflect on the direction we are heading with respect to detection and surveillance for CKD, lest we find ourselves in a situation akin to the morass of screening for Prostate Cancer. In Prostate Cancer we found an “epidemic” of Prostate Cancer was associated with the introduction of the PSA test in 1986, but had a very limited effect on the death rate. Prostate Cancer screening has become the “poster child for the problem of over-diagnosis in cancer” (1). Let us hope that CKD screening does not suffer the same fate.

    Dick Glassock

    Welch G, Schwartz LM, Woloshin S. Over-Diagnosed- making people sick in the pursuit of health. Beacon Press, Boston. 2011. page 60.

  2. Joanne Bargman said,

    April 25, 2011 @ 6:54 am

    Dick: As usual, a very trenchant and thoughtful analysis. It is always interesting to see how words get easily adopted into the vernacular. I have to vent here: suddenly, I think started by United Airlines, we have the redundant “do” in every sentence. “We DO ask that you stow your luggage…” “We DO thank you for flying United” and now Air Canada is using the United “do” in every announcement also. What’s with this? (Count the “do’s” next time you fly.)
    Yes, you are right, it isn’t an epidemic. Perhaps the only good outcome of using that word is that it will stir more residents to choose nephrology as a subspecialty.
    Joanne


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