By Louis Kuritzky, MD, Clinical Assistant Professor, University of Florida, Gainesville, and Associate Editor, Internal Medicine Alert
Hemochromatosis and Iron-Overload Screening
Hemochromatosis (HCRM) is something of an enigma to clinicians, since despite being recognized as having a gene frequency more common than any other known heritable disorder (1/10), HCRM symptoms and target organ damage are often sufficiently subtle or non-specific that the disorder goes unrecognized. Because many of the clinical consequences of HCRM are able to be reversed, or at least halted by appropriate treatment (phlebotomy), it is important to heighten clinician awareness of the disorder.
The HEIRS study (Hemochromatosis and Iron Overload Screening study) has screened for the prevalence, genetic determinants, and clinical impact of HCRM in diverse populations from 6 metropolitan areas: Washington, DC, Birmingham, Alabama, Irvine, California, Portland, Oregon, Honolulu, Hawaii, and Ontario, Canada. The population screened was comprised of White, Native American, Hispanic, Black, Pacific Islander, Asian, and multiethnic individuals (n = 99,711). Laboratory data included serum iron, iron-binding capacity, ferritin, transferrin saturation, and the genetic mutation most commonly associated with HCRM (HFE C282Y) .
Overall, 3 persons per thousand were homozygous for the C282Y mutation; amongst persons homozygous for C282Y (who had not been previously diagnosed with HCRM), an elevated ferritin was found in 88% of men and 57% of women. The population most frequently affected was non-Hispanic whites, although all populations had some affected persons. There remains a substantial body of individuals with undiagnosed HCRM whose clinical syndromes could be prevented or at least modified by appropriate identification and treatment.
Adams PC, et al. N Engl J Med. 2005; 352:1769-1778.
RSV Infection in Elderly and High-Risk Adults
Clinicians may think of respiratory syncytial virus (RSV) as a pathogen generally involved in infectious diseases of childhood. The first reports of RSV causing serious illness in older adults began in the 1970s, when RSV was recognized as the pathogen responsible for outbreaks in long-term care facilities. To obtain a clear assessment of the role of RSV infections, a population which included healthy community dwelling elders (n = 608), high-risk adults (eg, persons with underlying COPD or heart disease, n = 540), and adults admitted to the hospital for pneumonia (n = 1,388) was studied using multiple techniques (including PCR) to confirm the presence of RSV. For purposes of comparison, similar methods to identify influenza A virus were simultaneously used. The populations (in Rochester, MN) were prospectively followed for 4 winter seasons, 1999-2003.
Amongst high-risk adults, 4-10% incurred RSV infection annually. Similarly, in community dwelling elderly, 3-7% developed RSV infection annually. Overall, RSV was responsible for 10.6% of hospitalized pneumonias, and was identified in 11.4% of COPD admissions; 5.4% of CHF admissions, and 7.2% of asthma admissions were attributed to RSV. On a comparative basis, influenza A and RSV were responsible for essentially equivalent impact upon hospital expenditures and overall mortality.
The substantial epidemiologic burden of RSV has been insufficiently recognized. An RSV vaccine could provide an important public health benefit.
Falsey AR, et al. N Engl J Med. 2005;352:1749-1759.
BNP, CRP, and Urinary Albumin as Predictors of Mortality and Cardiovascular Events in Older Adults
Traditional risk factors for mortality and cardiovascular events such as blood pressure, lipids, and glucose provide excellent stratification opportunities for general populations. Unfortunately, not all important endpoints are directly attributable to currently recognized risk factors, and even when risk factors are effectively modified, the at-risk population is not returned to the same level of risk as persons without these same risk factors. Hence, so-called ‘novel’ risk factors have been sought to enhance the predictive value of available risk stratification tools.
C-reactive protein (CRP), brain natriuretic peptide (BNP), and albumin-to-creatinine ratio (ACR), have each demonstrated some predictive value in specifically defined populations. BNP levels have predictive ability even in healthy individuals.
A Danish population of 764 ostensibly healthy adults aged 50-89 was followed for 5 years, after obtaining baseline BNP, CRP, and urinary albumin-to-creatinine ratio.
Mortality risk was best predicted by BNP, with a hazard ratio of 1.96 (vs 1.88 for ACR, and 1.46 for CRP); similarly, BNP was more strongly associated with the first cardiovascular event, followed by ACR and then CRP.
Although CRP has enjoyed much more current popular discussion amongst clinicians, in healthy populations BNP and ACR provide better prognostic information.
Kistorp C, et al. JAMA. 2005;293: 1609-1616.
Because many of the clinical consequences of hemochromatosis are able to be reversed, or at least halted by appropriate treatment (phlebotomy), it is important to heighten clinician awareness of the disorder.
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