National Ambulatory Medical Care Survey: 2001 summary

OBJECTIVE: This report describes ambulatory care visits made to physician offices in the United States. Statistics are presented on selected characteristics of the physician's practice, the patient, and the visit. Results highlighting new items on continuity of care are presented. They include whether the visit was the first or a followup for a problem, number of visits to this provider in the past 12 months for established patients, and whether other physicians shared care for the patient's problem. The report also highlights estimates of practice characteristics for office-based physicians. METHODS: The data presented in this report were collected from the 2001 National Ambulatory Medical Care Survey (NAMCS). NAMCS is part of the ambulatory care component of the National Health Care Survey that measures health care utilization by various types of providers. NAMCS is a national probability sample survey of visits to office-based physicians in the United States. Sample data are weighted to produce annual national estimates. Selected trends from the 1992 and 1997 NAMCS are also presented. RESULTS: During 2001, an estimated 880.5 million visits were made to physician offices in the United States, an overall rate of 314.4 visits per 100 persons. From 1992 through 2001, the visit rate for persons 45 years of age and over increased by 17%, from 407.3 to 478.2 visits per 100 persons. The mean age of patients at each office visit has steadily increased from 1992 through 2001 as has the mean number of diagnoses rendered and the overall drug mention rate. The visit rate to physician offices in metropolitan statistical areas (MSAs) (338.3 visits per 100 persons) was significantly larger than the rate in non-MSAs (218.0 visits per 100 persons). Females had a higher visit rate compared with males, and white persons had a higher rate than black or African-American persons. Half of all office visits were to the patient's primary care physician (PCP). Of the visits to physicians other than the patient's PCP, about one-third (32.6 percent) were referrals. About 1 in 10 office visits were made by new patients (11.8 percent), down 20% since 1992. More than one physician shared the care for the patient's condition at about one-fifth of the office visits. Of all visits made to offices in 2001, 58.8 percent listed private insurance as the primary expected source of payment, followed by Medicare (21.8 percent) and Medicaid and/or State Children's Health Insurance Program (7.2 percent). For preventive care visits, the female visit rate was over 75% higher than the rate for males (67.1 versus 37.7 visits per 100 persons). Essential hypertension, arthropathies, acute upper respiratory infection, and diabetes mellitus were the leading illness-related primary diagnoses. There were an estimated 99.8 million injury-related visits in 2001, or 35.6 visits per 100 persons. Diagnostic and screening services were ordered or provided at 82.8 percent of visits, therapeutic and preventive services were ordered or provided at 41.4 percent of visits, and medications were prescribed or provided at 61.9 percent of visits. On average, 2.4 medications were ordered or provided at each office visit with any mention of a medication. The leading therapeutic class for drugs mentioned at office visits included cardiovascular-renal drugs (14.7 percent of mentions) and pain-relieving drugs (12.1 percent of mentions). A physician was seen at a majority of visits (95.8 percent), and a registered or licensed practical nurse was seen at 31.3 percent of visits. From 1992 through 2001, changes were observed in the leading diagnoses, therapeutic drug classes, and drug mentions. Physician estimates revealed that primary care physicians were twice as likely as specialists to make home visits during an average week of work; when they conducted them, they made twice as many (6 versus 2-3 visits per week) as specialists. Approximately 3 in 10 physicians reported not accepting new capitated, privately insured patients, whereas only 6.8 percent did not accept noncapitated, privately insured patients.     

New test to assess pilot's vision following refractive surgery

BACKGROUND: All forms of corneal refractive surgery can sometimes cause an increase in optical aberrations and scattered light, which can affect visual performance. The purpose of this study was to develop a suitable test that was sensitive to retinal image degradation in subjects who have undergone excimer laser refractive surgery and that was also relevant to visual demands in commercial aviation. METHODS: Assessment of the visual environment and the tasks involved in piloting a commercial aircraft formed the basis for the selection of the test parameters. The new contrast acuity assessment (CAA) test covers a functional visual field of +/-5 degrees and is based on minimum spatial vision requirements for commercial pilots. RESULTS: Data measured in 100 normal subjects were used to define the 'standard normal observer' and the range of variation for the parameters of the test. This approach makes it possible to quickly establish whether a given subject's performance falls within the range of the standard normal observer. The test is also administered under low ambient illumination since flying at night involves mesopic levels of light adaptation when the pupil size is large and the effects of aberrations and scattered light are therefore more pronounced. CONCLUSION: The results of the test are simple to interpret and reveal visual performance that falls outside the normal range as a result of either significant degradation of retinal image quality (caused by increased aberrations and scattered light) or abnormal processing of visual information in the retina and/or the visual pathway.     

Long-term time estimation is influenced by circadian phase

The adaptive significance of a putative time sense in humans remains unclear as do the factors that underlie the capacity to gauge the passage of time. Here we show that the subjective assessment of relatively long durations varies systematically as a function of time of day. Specifically, the subjective clock ran relatively faster when the circadian oscillation of body temperature was on the rise and relatively slower on the declining portion of the temperature curve. The overall result was a rather labile clock that, on average, ran slow relative to physical time. The results provide a glimpse into an underexplored aspect of how humans use their endogenous clocks in the most fundamental way--to gauge the passage of time.     

Obesity is associated with increased levels of circulating hepatocyte growth factor

OBJECTIVES: This study evaluated whether obesity in humans was associated with an increase in circulating hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) levels. BACKGROUND: Obesity acts as a cardiovascular risk factor by mechanisms that are not fully understood. Adipose tissue is able to secrete multiple cytokines and growth factors ex vivo. We hypothesized that the increased presence of adipose tissue in obese subjects results in systemic elevations of the mitogenic factors HGF and VEGF. METHODS: Blood samples were obtained from lean (n = 21) and obese (n = 44) volunteers. Serum HGF and VEGF levels were assessed by enzyme-linked immunoadsorbent assay. Insulin and fasting glucose levels were measured to evaluate insulin sensitivity. Conditioned medium of adipose cells was assayed for HGF secretion. RESULTS: Serum HGF levels in obese subjects were more than three-fold higher than those of lean subjects (2,462 +/- 184 pg/ml vs. 765 +/- 48 pg/ml, p < 0.0001). The VEGF levels were not significantly elevated in obese subjects (135 +/- 31 pg/ml vs. 128 +/- 37 pg/ml). The HGF concentrations, but not VEGF concentrations, were significantly correlated with body mass index (BMI) (p < 0.0001, r = 0.74). The observed increases in HGF concentrations of obese subjects were not secondary to insulin resistance or hypertension. Freshly isolated human adipose cells secreted HGF. CONCLUSIONS: Our results indicate that obesity is associated with a marked increase in circulating HGF levels, which correlate linearly with BMI. Because vascular growth factors have been associated with the pathogenesis of atherosclerosis, the possible role of such humoral factors as a link between obesity and cardiovascular disease is very intriguing.     

Comparison of Meropenem MICs and Susceptibilities for Carbapenemase-Producing Klebsiella pneumoniae Isolates by Various Testing Methods

We describe the levels of agreement between broth microdilution, Etest, Vitek 2, Sensititre, and MicroScan methods to accurately define the meropenem MIC and categorical interpretation of susceptibility against carbapenemase-producing Klebsiella pneumoniae (KPC). A total of 46 clinical K. pneumoniae isolates with KPC genotypes, all modified Hodge test and bla_KPC positive, collected from two hospitals in NY were included. Results obtained by each method were compared with those from broth microdilution (the reference method), and agreement was assessed based on MICs and Clinical Laboratory Standards Institute (CLSI) interpretative criteria using 2010 susceptibility breakpoints. Based on broth microdilution, 0%, 2.2%, and 97.8% of the KPC isolates were classified as susceptible, intermediate, and resistant to meropenem, respectively. Results from MicroScan demonstrated the most agreement with those from broth microdilution, with 95.6% agreement based on the MIC and 2.2% classified as minor errors, and no major or very major errors. Etest demonstrated 82.6% agreement with broth microdilution MICs, a very major error rate of 2.2%, and a minor error rate of 2.2%. Vitek 2 MIC agreement was 30.4%, with a 23.9% very major error rate and a 39.1% minor error rate. Sensititre demonstrated MIC agreement for 26.1% of isolates, with a 3% very major error rate and a 26.1% minor error rate. Application of FDA breakpoints had little effect on minor error rates but increased very major error rates to 58.7% for Vitek 2 and Sensititre. Meropenem MIC results and categorical interpretations for carbapenemase-producing K. pneumoniae differ by methodology. Confirmation of testing results is encouraged when an accurate MIC is required for antibiotic dosing optimization.Carbapenems are considered first-line therapy for infection with multidrug-resistant Enterobacteriaceae (14). However, the increasing emergence of serine-based carbapenemase-producing Klebsiella pneumoniae (KPC) worldwide is of growing concern. This problem is particularly worrisome due to the fact that this K. pneumoniae is one of the leading causes of hospital-acquired infections in severely ill patients, and few antibiotics retain microbiological activity against isolates that produce bla_KPC (15). Additionally, studies have demonstrated increased mortality rates in patients infected with carbapenem-resistant Enterobacteriaceae compared with those infected with susceptible strains (1, 12, 13).Detection of KPC based strictly on susceptibility testing is challenging due mostly to the heterogeneous expression of β-lactam resistance (15). Many automated systems report KPC as susceptible to meropenem, and while some isolates truly are, the MICs for most KPC are above the Food and Drug Administration (FDA) susceptibility breakpoint (4 μg/ml) (11). To address testing and reporting issues, the Clinical Laboratory Standards Institute (CLSI) Subcommittee on Antimicrobial Susceptibility Testing changed the susceptibility breakpoint for meropenem, imipenem, and doripenem to ≤1 μg/ml against Enterobacteriaceae in January 2010 (8). At the time of writing, the FDA breakpoint remained at ≤4 μg/ml for meropenem.Given the lack of options for antibiotics that retain susceptibility against pathogens that produce KPC, selection of a dosing regimen that could potentially treat infections caused by these organisms depends on the ability to accurately determine the antibiotic MIC. With respect to KPC, the accurate determination of the meropenem MIC may permit the application of pharmacodynamic principles to dosing regimen optimization by administering higher doses and using prolonged or continuous infusions, as has been accomplished against other resilient bacteria (3, 10, 14).Herein, we describe the levels of agreement between commonly used testing methods (broth microdilution [BMD], Etest, Vitek 2, Sensititre, and MicroScan) in their abilities to accurately determine the meropenem MIC and further classify categorical susceptibilities of carbapenemase-producing K. pneumoniae isolates based on the 2010 CLSI breakpoints compared with FDA breakpoints.