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PubMed2004

Commercially available pedometers: considerations for accurate step counting.

BACKGROUND: Many commercially available pedometers undercount, especially at slower speeds. We examined the effects of age, obesity, and self-selected walking speed on pedometer accuracy. We also compared the accuracy of piezoelectric and spring-levered pedometers at slow walking speeds. METHODS: Study 1: 259 subjects walked on a motorized treadmill at two self-selected walking speeds. Steps were counted using a spring-levered pedometer. Study 2: 32 subjects walked on a motorized treadmill at slow walking (1.0-2.6 MPH) speeds. Steps were counted using spring-levered and piezoelectric pedometers. RESULTS: Study 1: self-selected walking speed and pedometer accuracy decreased with increasing age, weight, and body mass index (BMI). Accuracy was 71% below 2.0 MPH, 74-91% between 2.0 and 3.0 MPH, and 96% above 3.0 MPH. Decreased accuracy was best predicted by increasing age. Study 2: between 1.8 and 2.0 MPH, the accuracy of the piezoelectric pedometer (>97%) exceeded that of the spring-levered pedometers (52-95%). Even at 1.0 MPH, accuracy of the piezoelectric pedometer (56.4 +/- 33.8%) was superior to the spring-levered pedometers (7-20%). CONCLUSION: Accuracy of all pedometers tested exceeded 96% at speeds 3.0 MPH, but decreased at slower walking speeds. In individuals that naturally ambulate at slower walking speeds (e.g., elderly), we recommend the use of more sensitive (e.g., piezoelectric) pedometers.

Adult↗
PubMed1994

Nevus counting as a risk factor for melanoma: comparison of self-count with count by physician.

BACKGROUND: The number of total body nevi is a major risk marker for malignant melanoma. No previous study has evaluated the accuracy of whole body large nevus (> or = 5 mm) self-counts. OBJECTIVE: Our purpose was to evaluate the accuracy of large nevus self-counts by sex, age, educational level, body site, family history of skin cancer, and nevus characteristics. METHODS: Self-counting of large nevi by 125 patients was compared with physician counting, with attention to nevus characteristics. RESULTS: Overall, 79% of the self-counts agreed to within +/- 3 nevi of the physician's count. Analysis of variance revealed that the presence of nonpigmented or flat nevi significantly increased the chance of subject undercount, as did male sex. CONCLUSION: Self-counts of large nevi are comparable to physician's counts and may be useful for melanoma screening.

Adult↗
PubMedDate not supplied

Comparison of rat epididymal sperm counts by IVOS HTM-IDENT and hemacytometer.

Epididymal sperm counts, a common measurement in male reproductive toxicity studies, are routinely determined using a hemacytometer. Recently, computer assisted methods for automated sperm counts have been developed. In the present study we evaluated an automated system, the TOX IVOS (Hamilton Thorne Research, Beverly, MA) HTM-IDENT option, that utilizes a DNA-specific stain and fluorescence illumination to identify sperm for enumeration. Cauda and caput epididymal sperm counts were determined in 48 adult male Sprague-Dawley rats, using both the hemacytometer and HTM-IDENT. The mean hemacytometer and HTM-IDENT counts (+/- SD) were 250 +/- 43 and 254 +/- 52 million, respectively, for cauda sperm, and 123 +/- 13 and 127 +/- 18 million, respectively, for caput sperm. The average coefficient of variation using the hemacytometer was 13.8% as compared to 17.3% for the HTM-IDENT. Comparison of the machine count and a visual count from the Display Statics screen of the HTM-IDENT indicated that when two or more sperm heads touched or overlapped, the machine counted them as one. Manual (visual) and machine counts when compared over a range of nine concentrations from 3.7 to 47.8 million/mL differed by 4 to 12% at the lowest to highest concentration. The concentration of epididymal sperm samples used in comparing the two counting methods ranged from 5.8 to 17.7 million/mL. Therefore, the HTM-IDENT undercounting error attributable to sperm heads touching was less than 6%. Overall the data indicate good agreement between the HTM-IDENT and the hemacytometer counts. Furthermore, both counting time and technician fatigue were markedly reduced. Thus the HTM-IDENT option improves the efficiency of epididymal sperm counting without loss of precision.

Animals↗
PubMed1999

Chinese traditional medicine and abnormal sex ratio at birth in China.

A study of the abnormal sex ratio at birth in China reveals that it is not an entirely new phenomenon that emerged since the 1980s, but is simply more visible at present. Deliberate intervention to determine the sex of children has existed in the past few decades, at least in certain groups. Apart from modern medical methods, traditional Chinese medical practice is shown to be highly accurate in identifying the sex of a fetus. This may lead to sex-selective abortion and an abnormal sex ratio at birth. The possible causes of the abnormal sex ratio at birth include not only the real imbalance due to the disturbance of social factors, but also a spurious one attributable to the undercounting of female births. The real magnitude of the imbalance has been exaggerated by statistical error. The phenomenon is a complicated one reflecting the comprehensive socioeconomic setting. Among these factors, the stage of the fertility transition is one of the most decisive.

Child↗
PubMed2005

Under-notification of giardiasis in Auckland, New Zealand: a capture-recapture estimation.

Estimation of the degree of undercount is important for disease surveillance. Capture-recapture techniques are now being used to evaluate the completeness of disease ascertainment. This study estimated the level of under-notification of giardiasis in the Auckland adult population using a capture-recapture method. Two independent datasets of giardiasis cases > or = 15 years were generated from the 1998-1999 Auckland Giardiasis Study (AGS) case database and cases notified to Auckland Regional Public Health Services (ARPHS) for the same period of time. Cases were matched and under-notification was estimated using a two-sample capture-recapture method. During the 12-month period, 199 cases participated in the AGS and 413 cases were notified to ARPHS. The capture-recapture calculation indicated that only 49% of cases were notified. Under-notification by a factor of 2 obscures the true burden of giardiasis. Socio-economic conditions and water quality may influence disease notification inversely. Capture-recapture techniques are useful in evaluating the completeness of surveillance.

Adolescent↗
PubMed1999

The epidemiology of Type 2 diabetes and its current measurement.

Type 2 diabetes is globally increasing in prevalence and is widely recognized as a major cause of morbidity and mortality, as well as being a burden to the health-care services. Planning for current and future diabetes services requires up-to-date prevalence information. The enumeration of Type 2 diabetes is, however, surprisingly difficult. Large numbers of people are undiagnosed, and those known cases have variable loci of care. Traditional techniques include cross-sectional diagnostic surveys, postal or house-to-house surveys and cohort surveys. All are time-consuming and expensive, and may potentially undercount. The use of multiple patient lists (e.g. hospital clinic data, general practitioner (GP) lists, prescribing information, etc.) can, however, increase accuracy and, if the data are computerized, may be rapid and inexpensive. A new and potentially exciting tool to utilize multiple lists in Type 2 diabetes prevalence assessment is known as 'capture-recapture'. In this, statistical models are used to estimate prevalence from the degree of overlap between lists. Capture-recapture is emerging as a valuable tool in the epidemiological assessment of Type 2 diabetes.

Animals↗
PubMed2000

The multiple-race population of the United States: issues and estimates.

This paper presents national estimates of the population likely to identify with more than one race in the 2000 census as a result of a new federal policy allowing multiple racial identification. A large number of race-based public policies-including affirmative action and the redistricting provisions of the Voting Rights Act-may be affected by the shift of some 8-18 million people out of traditional single-race statistical groups. The declines in single-race populations resulting from the new classification procedure are likely to be greater in magnitude than the net undercount in the U.S. census at the center of the controversy over using census sampling. Based on ancestry data in the 1990 census and experimental survey results from the 1995 Current Population Survey, we estimate that 3. 1-6.6% of the U.S. population is likely to mark multiple races. Our results are substantially higher than those suggested by previous research and have implications for the coding, reporting, and use of multiple response racial data by government and researchers. The change in racial classification may pose new conundrums for the implementation of race-based public policies, which have faced increasing criticism in recent years.

Censuses↗
PubMed2002

The dynamics of the population sex ratio in India, 1971-96.

This paper reconstructs the trend in the population sex ratio in India between 1971 ad 1996 from available information on changes in sex differentials in mortality in the country since the beginning of the century. It is estimated that, although the mortality of females relative to that of males in India has improved since 1968, the population sex ratio increased between 1971 and 1981, stayed constant between 1981 and 1991, and started to decrease only after 1991. This implies that the recorded decrease and increase in the periods 1971-81 and 1981-91 respectively were both spurious and were the results of undercounts of females in 1971 and 1991. Another implication of this finding is that, owing to the lagged effect of past mortality on current trends in the population sex ratio, this ratio is a bad proxy for use in the study of changes in differential mortality by sex.

History, 20th Century↗
PubMed1999

Detection of illicit opioid and cocaine use in methadone maintenance treatment.

Urine toxicology is the gold standard for estimating the prevalence of illicit drug use in methadone maintenance treatment (MMT). The frequency of urine testing may be crucial for establishing accurate use rates. Infrequent testing may lead programs to undercount active drug users and to target interventions too narrowly. This study compared results from frequent testing (twice per week) versus less frequent testing of 166 patients at four MMT programs. As part of a research study, all patients were tested by research staff for opioid and cocaine use twice per week on a fixed schedule for 10 weeks. During the same period, the four MMT programs tested the patients according to their standard protocols, approximately weekly (one program) or every 3-4 weeks (three programs). The research tests identified approximately 50% more illicit opioid users and 70% more cocaine users than the less frequent program tests. Patients who were drug positive according to the research tests but drug negative according to the program tests tended to be infrequent users. The data suggest that standard urine testing practices in MMT programs may result in underestimates of the prevalence of opioid and cocaine use. More frequent testing, even for time-limited periods, should produce more accurate depictions of drug use prevalence and help indicate the direction of interventions.

Adult↗
PubMed1993

Ascertainment corrected rates: applications of capture-recapture methods.

Accurate rates, though fundamental to epidemiology, are often very difficult to obtain. Incidence, prevalence, and mortality rates have traditionally been established through either passive reporting surveillance systems, through active surveillance systems, or by a combination of the two methods. Typically, when researchers employ these approaches they do not formally evaluate or correct for the degree of underascertainment. Undercount of cases is a potent determinant of rates which we cannot continue to ignore. We believe all rates should be adjusted for underascertainment in order to achieve a truer picture of the risk and risk factors of disease. Here, we present a procedure to ascertainment correct rates based upon well established capture-recapture methods.

Epidemiologic Methods↗
PubMed1999

Evaluating the reported prevalence of type 2 diabetes mellitus by the Oguni diabetes registry using a two-sample method of capture-recapture.

BACKGROUND: Capture-recapture methods have been widely employed in the study of wildlife populations and have recently been applied to count various human diseases and conditions. We have estimated the prevalence of type 2 diabetes mellitus by adjusting for the degree of undercount using a two-sample model of capture-recapture among men and women aged 50-69 in Oguni town, Japan. METHODS: Oguni town diabetes registry data were utilized as the first source. In the registry, only those who had experienced fasting plasma glucose of > or = 7.8 mmol/l (140 mg/dl) or 2 h plasma glucose after a 75 g oral glucose tolerance test (OGTT) of > or = 11.1 mmol/l (200 mg/dl) were counted as having diabetes. A second source was a sample study selecting 200 men and 200 women aged 50-69 randomly, which was conducted in August 1991. A 75 g OGTT was done in the morning. The 1985 World Health Organization criteria were used to classify the diabetes status of the participants. A two-sample model of capture-recapture methods was employed to estimate the total number of cases of diabetes and determine the ascertainment rates of the registry. RESULTS: The prevalence estimated by the diabetes registry was 7.1%. The prevalence from the sample study was 8.8% with a participation rate of 74%. Estimated prevalence employing the capture-recapture method was 13.1%. The ascertainment rate of the registry was 53.8%. CONCLUSIONS: Little is known about the prevalence of type 2 diabetes in local areas in Japan, the US and the world. Capture-recapture methods are likely to provide a means to accurately assess the prevalence of diabetes.

Aged↗
PubMed2002

Are deaths within 1 month of cancer-directed surgery attributed to cancer?

BACKGROUND: Cancer mortality should include not only deaths from cancer but also deaths from cancer treatment. By convention, deaths within 30 days of a surgical procedure are considered treatment-related deaths in the calculation of operative mortality-that is, the chance of dying from surgery. How cause of death is attributed in patients who die within 1 month of cancer-directed surgery is unknown. METHODS: The National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program data from 1994 through 1998 were used to examine the cause of death in patients diagnosed with one of 19 common solid tumors who had died within 1 month of diagnosis and had also received cancer-directed surgery. We determined the proportion of deaths not attributed to the cancer and the magnitude of the undercount in cancer-specific mortality. RESULTS: Among 4135 patients with only one cancer who died within 1 month of diagnosis and cancer-directed surgery, the proportion of deaths not attributed to the coded cancer was 41% (1714/4135), ranging from 13% (1/8) for cervical cancer to 81% (13/16) for laryngeal cancer. Selected intermediate values include 25% (14/56) for esophageal cancer, 34% (177/525) for lung cancer, 42% (719/1695) for colorectal cancer, 59% (110/186) for breast cancer, and 75% (80/106) for prostate cancer. Restricting the analysis to deaths following specific major procedures (e.g., esophagectomy, pneumonectomy, colectomy) had little effect on the findings. If all deaths within 1 month of cancer-directed surgery were attributed to cancer, cancer mortality would rise about 1%. CONCLUSION: Some deaths that are conventionally attributed to surgery are not being attributed to the cancer for which the surgery was performed. Although the estimated effect of this misclassification on overall cancer mortality is modest, it may be indicative of more widespread confusion about how to code treatment-related deaths of patients with cancer.

Databases as Topic↗
PubMed1996

Ethnic variation in the incidence of stomach cancer in Illinois, 1986-1988.

Wide ethnic and geographic variation in stomach cancer incidence has been reported in Eastern and Western countries. Stomach cancer is reported to be the most common malignant neoplasm in Asia, specifically, China, Japan, and Korea. In contrast, stomach cancer incidence in the United States among Caucasians is low and among blacks, moderate to low. Only one other study has directly compared the rates of stomach cancer in the three ethnic groups (i.e., white, African American, and immigrant Korean) living in the same region. The authors extend their investigation by comparing the incidence rate of stomach cancer among the same three ethnic groups in the state of illinois from 1986 to 1988. In this study, the incidence of stomach cancer was observed to be lowest in whites, intermediate in African Americans, and highest in immigrant Koreans. The overall 3-year cumulative incidence rate from 1986 to 1988 was 62.6/100,000 (95% confidence interval (CI) 38.6-86.7), 28.2/100,000 (95% CI 25.7-31), and 22.5/100,000 (95% CI 21.5-23.5) for immigrant Koreans, African Americans, and whites, respectively. The 3-year age-adjusted cumulative incidence rate for immigrant Koreans (172/100,000) was approximately four-and eightfold higher than for African Americans (41/100,000) and whites (21/100,000). The incidence of stomach cancer increased as a function of age in both sexes. Although a higher rate was observed in males than in females, these rates were four-and eightfold higher in African Americans and immigrant Koreans, when compared with their white counterparts in both sexes. Despite a substantial reduction of stomach cancer incidence in the United States and other Western countries, it remains the most frequent malignancy in native and immigrant Koreans. The high rate of stomach cancer in immigrant Koreans compared with African Americans and white populations residing in Illinois indicates either a drastically disproportionate undercount of immigrant Koreans in the 1990 census or a profound genetic-environmental interaction.

Adolescent↗
PubMed1993

Survival and mortality patterns of an acquired immunodeficiency syndrome (AIDS) cohort in New York State.

The survival experience and causes of death of acquired immunodeficiency syndrome (AIDS) patients were studied using a cohort of 3,699 AIDS patients in New York State, excluding New York City, whose illness was diagnosed before January 1990 at age 13 years or older. The median length of survival for all cases was 11.5 months, and survival increased over time from 5.3 months pre-1984 to 9.3 months in 1984-1986 and to 13.2 months in 1987-1989. In a Cox proportional hazards model, risk of dying was higher for persons aged 35 years or more at diagnosis and for persons with a diagnosis other than Pneumocystis carinii pneumonia or Kaposi's sarcoma whose illness was diagnosed before 1986. In this AIDS cohort, 2,834 (77 percent) persons died before 1991; 87 percent of the death certificates listed human immunodeficiency virus (HIV)/AIDS or an AIDS indicator disease as one of the multiple causes of death. The finding that 13 percent of the death certificates did not mention AIDS/HIV suggests that use of death certificates alone to count HIV-related deaths would result in an undercount. The recent expansion of the federal AIDS case definition is expected to add HIV-infected persons who die from conditions, such as recurrent pneumonia, that were not included in the earlier definition.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Efficiency and accuracy of disease monitoring systems: application of capture-recapture methods to injury monitoring.

Capture-recapture methods were employed to determine the most accurate and efficient approaches to monitor adolescent injuries. Multiple sources were used to ascertain cases of adolescent injuries that occurred between September 1 and December 31, 1991, in a single school district in metropolitan Pittsburgh, Pennsylvania. Eliminating the duplicate cases between the sources revealed 144 verified injuries; 127 (88.2%) were identified by student monthly recalls, 33 (22.9%) by daily attendance records, 58 (40.3%) by medical excuses, and 72 (50.0%) by a 4-month student recall. Capture-recapture analyses were undertaken to assess potential dependencies between the sources, to estimate the degree of underascertainment in the population, and to evaluate the efficiency of the individual sources and the combinations between them. It was estimated that 91% of the cases in the population were ascertained when all four methods of case finding were utilized. Furthermore, the analysis indicated that accurate injury estimates could be achieved using combinations of only two or three of the sources. An analysis of the efficiency of the methods of ascertainment revealed a trade-off between effort (the number of hours needed to identify cases) and the precision (coefficient of variation) of the injury estimates. Capture-recapture analysis not only provided an approach to evaluate and adjust for undercount but also offered a formal means to evaluate the most efficient combination of the sources to maximize completeness while minimizing effort. The use of these techniques has the potential to evaluate and improve injury surveillance as well as other disease monitoring systems.

Adolescent↗
PubMedDate not supplied

Costs of occupational injuries in agriculture.

OBJECTIVE: This study was conducted to estimate the costs of job-related injuries in agriculture in the United States for 1992. METHODS: The authors reviewed data from national surveys to assess the incidence of fatal and non-fatal farm injuries. Numerical adjustments were made for weaknesses in the most reliable data sets. For example, the Bureau of Labor Statistics (BLS) Annual Survey estimate of non-fatal injuries is adjusted upward by a factor of 4.7 to reflect the BLS undercount of farm injuries. To assess costs, the authors used the human capital method that allocates costs to direct categories such as medical expenses, as well as indirect categories such as lost earnings, lost home production, and lost fringe benefits. Cost data were drawn from the Health Care Financing Administration and the National Council on Compensation Insurance. RESULTS: Eight hundred forty-one (841) deaths and 512,539 non-fatal injuries are estimated for 1992. The non-fatal injuries include 281,896 that led to at least one full day of work loss. Agricultural occupational injuries cost an estimated $4.57 billion (range $3.14 billion to $13.99 billion) in 1992. On a per person basis, farming contributes roughly 30% more than the national average to occupational injury costs. Direct costs are estimated to be $1.66 billion and indirect costs, $2.93 billion. CONCLUSIONS: The costs of farm injuries are on a par with the costs of hepatitis C. This high cost is in sharp contrast to the limited public attention and economic resources devoted to prevention and amelioration of farm injuries. Agricultural occupational injuries are an underappreciated contributor to the overall national burden of health and medical costs.

Accidents, Occupational↗
PubMed1999

Capture-recapture-adjusted prevalence rates of type 2 diabetes are related to social deprivation.

We examined the prevalence of type 2 diabetes and social deprivation in one urban district in Liverpool from October 1995 to September 1996 inclusive. This area has a stable Caucasian population of 176, 682. Lists were made of all known diabetics attending six different medical points of contact during the year, and were condensed and aggregated to eliminate duplicates. From postcode data, each patient was assigned to residence in one of the 14 electoral wards in the district, for which demographic structure and standardized measures of social deprivation were known (Townsend index). The crude period prevalences of type 1 and type 2 diabetes were estimated for each ward. Crude prevalence data were then corrected by applying capture-recapture (CR) techniques to the different patient datasets to allow for undercount. The crude period prevalence (95%CI) of diabetes was 1.5% (1.4-1.5%), or 2585/176, 682. The mean age of people with diabetes was not significantly different between electoral wards. The crude period prevalence of type 2 diabetes within individual wards ranged from 0.4% (0.3-0.6%) in the least deprived area to 4.1% (3.6-4.6%) in the most deprived area. The corresponding range of CR-adjusted period prevalence rates of type 2 diabetes was from 3.2% (2.8-3.6%) to 6.7% (6.1-7.4%), and there was strong correlation between both crude and CR-adjusted prevalence and social deprivation in each ward (r=0.76, p<0.001 for crude; and r=0. 49, p<0.005 for CR-adjusted prevalence). There was no correlation between the crude or CR-adjusted period prevalence rates of type 1 diabetes and Townsend index (r=0.14, p=NS). This strong correlation between the prevalence of type 2 diabetes and social deprivation has important implications for the planning of health-care delivery.

Adolescent↗
PubMed1993

Establishment of accurate incidence rates for head and spinal cord injuries in developing and developed countries: a capture-recapture approach.

Prevention of head and spinal cord injuries is defined as a reduction in the incidence of these disabilities. Accurate incidence data are fundamental to any prevention program. The current approaches toward determining incidence rates for head and spinal cord injuries are summarized. Previous research has focused on passive surveillance systems and population-based registries. An alternative system for monitoring the incidence of head injuries is discussed that uses a surveillance methodology called capture-recapture. This method employs multiple population-based sources to identify cases and uses the cases that overlap between the sources to estimate the degree of undercount in the population. This estimate in turn is used to produce an ascertainment-corrected incidence estimate. Through the use of methods such as capture-recapture, accurate monitoring of the incidence of head and spinal injuries across developing and developed countries is indeed feasible.

Bias↗