Monday, January 17, 2011

The Incidence Of Kidney Failure Due To Diabetes Is Down – But We Should Not Be Pleased

Diabetes mellitus is the most common cause of kidney failure that progresses to end stage renal disease (ESRD,) meaning that the person requires dialysis or kidney transplant. ESRD is chronic and life long, is complicated to treat, has a major negative effect on quality of life and the costs are high.

So it was good news when the Centers of Disease Control reported that the incidence of ESRD among diabetics had declined by about 35% over the ten years ending in 2007. The reasons for the decline are not known but a few assumptions seem reasonable. More and more patients now keep good control of their blood sugar with careful monitoring and many also keep their blood pressure under control with anti-hypertensive medications. Further, it has been shown that angiotensin-converting enzyme inhibitors (or ACE inhibitors) and angiotensin-receptor blockers (or ARBs) slow the decline of kidney function in those with diabetes and early kidney failure. It is believed that as many as 80% of these patients are taking ACE or ARBs – a good thing. All of these may be the factors that have led to this decline of diabetes to kidney failure; or there may be others as yet not appreciated.

But the news really is not so good. The decline in kidney failure incidence was offset by a much increased absolute number of individuals with diabetes developing kidney failure. Why? Because there are so many more individuals developing diabetes now than just a decade ago – so there are more people at risk of and therefore developing kidney failure.

We can be pleased that secondary prevention approaches are slowing the onset of kidney failure among those with diabetes but we should be aghast that so many of our fellow citizens are setting themselves up for a high risk of diabetes as a result of obesity.

The message - the real need is to accelerate efforts to stop the epidemic of obesity (excess consumption of not very nutritious food compounded with a sedentary lifestyle, including in adolescents.) Obesity is the primary culprit leasing to the rapidly rising number of individuals with diabetes.

Friday, January 14, 2011

The Shingles (Herpes Zoster) Vaccine Really Works But Many Older Folks Don’t Receive It - They Should

Herpes zoster (or shingles) is caused by the same virus that causes chicken pox. Zoster increases in incidence with advancing age. It is estimated that over 1 million Americans get shingles annually with the resulting acute discomfort and often chronic pain thereafter. A vaccine was introduced by Merck in 2006; the initial studies of 38,546 patients indicated that it reduced the incidence by about 50% and for those who still got shingles, the severity was lessened substantially. But acceptance of the vaccine has been slow. It seems that this is due to a combination of lack of knowledge that it is available and is effective; failure of physicians to inform their patients; and a fairly high cost of about $200, often not covered by insurance.

A new study was reported in JAMA January 12, 2011. Kaiser Permanente, Southern California and Centers for Disease Control and Prevention investigators evaluated 75,761 Kaiser members who had no underlying immunological disorder and who had been vaccinated between January, 2007 and December 2009. These were compared to a control group of 227,283 age matched members who had not been vaccinated.

Among the unvaccinated individuals, this study showed that, as anticipated, shingles incidence goes up with age from - 60-64 years of age (9.7 infections per 1000 person years) to over age 80 (17.3 per 1000 person years).

Vaccination reduced the frequency by about 50% from a total of 13.0 per 1000 person years to 6.4 per 1000 person years. This halving of incidence was found at all age intervals, indicating that the vaccine works as well in the very elderly as in “younger” individuals. The incidence of zoster was steady over time. For example, at one year, slightly more that 1% of the unvaccinated individuals had developed zoster compared to less that 0.05% in the vaccinated group; at two years the numbers were about 2 ½ % and 1%, respectively. During the time of patient follow-up, this can be stated as one case of herpes zoster was prevented with each 71 vaccinated. However, since the follow up was only about 1 ½ years for most individuals and since it is estimated that beginning at age 60 a person has a 20% lifetime risk of zoster, it is my presumption that it actually takes many fewer individuals vaccinated to prevent one episode of zoster over the rest of one’s life.

Not part of this study, the original Merck investigation demonstrated that many older people do not respond well to the vaccine with increases in antibody production. This finding is consistent with many others that those over 60 years of age respond much less well than do those who are younger. This raises the question as to whether it would be useful to measure antibody production after vaccination to determine who has and who has not responded well. Perhaps those who do not should get a second vaccination. This is an important issue for all vaccines in older people. The same occurs with influenza vaccine which is why, this year, the dose for older people was doubled. But perhaps there are other approaches as well to improving the response rates for those at increased risk in their older years who respond less well to vaccines.

The study makes clear that this vaccine is effective, including for those over 80 years of age where the incidence is the highest. Given the implications of herpes zoster in immediate and longer term suffering and the attendant costs, I believe this is a vaccine that essentially everyone over the age of 60 (other than immunocompromised individuals) should receive. Insurance should pay for it just as with the influenza vaccine.

Even if paid for out of pocket, it is worth it. Patients need to ask for it and doctors need to encourage it.

Tuesday, January 11, 2011

To Scan or Not To Scan for Early Lung Cancer

Lung cancer is the most common cancer other than skin cancer. The survival rate is still dismal so early diagnosis presumably could make an impact. Chest x-rays just do not have the sensitivity to find early lung cancer. Computed tomography (CT Scans) can detect very small lesions in the lung. Another study has now been completed and it was able to find many early cancers.

The National Cancer Institute funded this study that randomly allocated some 53,500 men and women at high risk (i.e., smoked about 1 pack or more cigarettes per day for 30 or more years) to either standard chest X-rays or low dose CT scans. Each person had a screening image taken annually for three years and were followed for an additional five years.

As of October, 2010, there were 649 cancers detected and 354 deaths in the CT group compared to 279 cancers and 442 lung cancer deaths in the X-ray group (obviously many of these latter cancer deaths were due to cancer NOT detected by the routine chest X-ray). The implication is that low dose CT scans detected cancer earlier resulting in successful therapy for many.

Lung cancer mortality per 100,000 was 246 and 308 for the CT group and the X-ray group respectively for a 20% reduction in lung cancer mortality.

But there are “buts” to the study. To save one life required 300 people to be screened. A CT scan costs at least $300 each, often much more. This means it cost $90,000 to save one life. Another “but” is CT screening detects lesions that are often not cancer. Indeed the false positive rate was about 25%. Since it requires a biopsy to prove it is benign, this adds not only risk and costs, but anxiety.

There is more information at

The take away for now is that in high risk individuals, low dose CT scans can pick up early lung cancer. But the combination of high false positives and high costs weigh against its routine use even in these patients.

Praise for Dr Schimpff

The craft of science writing requires skills that are arguably the most underestimated and misunderstood in the media world. Dumbing down all too often gets mistaken for clarity. Showmanship frequently masks a poor presentation of scientific issues. Factoids are paraded in lieu of ideas. Answers are marketed at the expense of searching questions. By contrast, Steve Schimpff provides a fine combination of enlightenment and reading satisfaction. As a medical scientist he brings his readers encyclopedic knowledge of his subject. As a teacher and as a medical ambassador to other disciplines he's learned how to explain medical breakthroughs without unnecessary jargon. As an advisor to policymakers he's acquired the knack of cutting directly to the practical effects, showing how advances in medical science affect the big lifestyle and economic questions that concern us all. But Schimpff's greatest strength as a writer is that he's a physician through and through, caring above all for the person. His engaging conversational style, insights and fascinating treasury of cutting-edge information leave both lay readers and medical professionals turning his pages. In his hands the impact of new medical technologies and discoveries becomes an engrossing story about what lies ahead for us in the 21st century: as healthy people, as patients of all ages, as children, as parents, as taxpayers, as both consumers and providers of health services. There can be few greater stories than the adventure of what awaits our minds, bodies, budgets, lifespans and societies as new technologies change our world. Schimpff tells it with passion, vision, sweep, intelligence and an urgency that none of us can ignore.

-- N.J. Slabbert, science writer, co-author of Innovation, The Key to Prosperity: Technology & America's Role in the 21st Century Global Economy (with Aris Melissaratos, director of technology enterprise at the John Hopkins University).