Using mixture models with linear predictors to identify incorrect gestational age in state birth records.

BACKGROUND: Birthweight distributions for early last-menstrual-period-based gestational ages are bimodal, and some birthweights in the right-side distribution are implausible for the specified gestational age. Mixture models can be used to identify births in the right-side distribution. The objective of this study was to determine which maternal and infant factors to include in the mixture models to obtain the best fitting models for New Jersey state birth records. METHODS: We included covariates in the models as linear predictors of the means of the component distributions and the proportion of births in each component. This allowed both the means and the proportions to vary across levels of the covariates. RESULTS: The final model included maternal age and timing of entry into prenatal care. The proportion of births in the right-side distribution was lowest for older mothers who entered prenatal care early, higher for teen mothers who entered prenatal care early, higher still for older mothers who entered prenatal care late, and highest for teens who entered prenatal care late. Over 44% of births were classified as incorrect reported gestational age. CONCLUSION: These results suggest that (1) including these two covariates as linear predictors of the means and mixing proportions gives the best model for identifying births with incorrect reported gestational age, (2) late entry into prenatal care is a mechanism by which erroneously short last-menstrual-period-based gestational ages are generated, and (3) including linear predictors of the mixing proportions in the model increases the validity of the classification of incorrect reported gestational age.

The national study to prevent blood exposure in paramedics: rates of exposure to blood.

OBJECTIVE: The purpose of this analysis is to present incidence rates of exposure to blood among paramedics in the United States by selected variables and to compare all percutaneous exposure rates among different types of healthcare workers. METHODS: A survey on blood exposure was mailed in 2002-2003 to a national sample of paramedics. Results for California paramedics were analyzed with the national sample and also separately. RESULTS: The incidence rate for needlestick/lancet injuries was 100/1,000 employee-years [95% confidence interval (CI), 40-159] among the national sample and 26/1,000 employee-years (95% CI, 15-38) for the California sample. The highest exposure rate was for non-intact skin, 230/1,000 employee-years (95% CI, 130-329). The rate for all exposures was 465/1,000 employee-years (95% CI, 293-637). California needlestick/lancet rates, but not national, were substantially lower than rates in earlier studies of paramedics. Rates for all percutaneous injuries among paramedics were similar to the mid to high range of rates reported for most hospital-based healthcare workers. CONCLUSIONS: Paramedics in the United States are experiencing percutaneous injury rates at least as high as, and possibly substantially higher than, most hospital-based healthcare workers, as well as substantially higher rates of exposure to blood on non-intact skin.

Management practices and risk of occupational blood exposure in U.S. paramedics: Needlesticks.

BACKGROUND: The purpose of this study was to present risk estimates for needlestick in U.S. paramedics and estimated risk ratios for selected management practices. METHODS: A mail survey was conducted among a national sample of U.S. paramedics in 2002-2003. RESULTS: The adjusted response rate was 55% (n = 2,664). The overall 12-month risk of needlestick was 6.7% (95% confidence interval, 5.4-7.9). Risk ratios for provision of safety-engineered medical devices and two supervisory behaviors that emphasized safe work practices ranged from 2.5 to 3.2. The protective effect of working in an environment that included both of the supervisory behaviors was greater than the protective effect of always being provided with safety devices. A sensitivity analysis indicated that the risk ratio estimates were unlikely to be inflated by nonresponse bias. CONCLUSIONS: These results suggest that greater provision of safety devices and interventions aimed at management practices that promote worker safety could substantially reduce the risk of needlestick among U.S. paramedics.

Blood exposure incidence rates from the North Carolina study of home care and hospice nurses.

BACKGROUND: Home care/hospice nurses may be at elevated risk of blood exposure because of the nature of their work and work environment. However, little is known about the incidence of blood exposure in this population. METHODS: A mail survey (n = 1,473) was conducted among home care/hospice nurses in North Carolina in 2006. RESULTS: The adjusted response rate was 69%. Nine percent of nurses had at least one exposure/year. Overall incidence was 27.4 (95% confidence interval: 20.2, 34.6)/100,000 visits. Nurses who had worked in home care < or =5 years had higher exposure rates than other nurses-seven times higher for needlesticks and 3.5 times higher for non-intact skin exposures. Nurses who worked part time/contract had higher exposure rates than nurses who worked full time-seven times higher for needlesticks and 1.5 times higher for non-intact skin exposures. The rates for part-time/contract nurses with < or =5 years experience were extremely high. Sensitivity analysis showed that it is unlikely that response bias had an important impact on these results. CONCLUSIONS: Approximately 150 North Carolina home care/hospice nurses are exposed to blood annually. If these results are representative of other states, then approximately 12,000 home care/hospice nurses are exposed each year nationwide. Improved prevention efforts are needed to reduce blood exposure in home care/hospice nurses. Am. J. Ind. Med. 52:99-104, 2009. (c) 2008 Wiley-Liss, Inc.

Blood exposure among paramedics: incidence rates from the national study to prevent blood exposure in paramedics.

PURPOSE: The aim of the study is to estimate incidence rates of occupational blood exposure by route of exposure (needlesticks; cuts from sharp objects; mucous membrane exposures to the eyes, nose, or mouth; bites; and blood contact with nonintact skin) in US and California paramedics. METHODS: A mail survey was conducted in a national probability sample of certified paramedics. RESULTS: Proportions of paramedics who reported an exposure in the previous year were 21.6% (95% confidence interval [CI], 17.8-25.3) for the national sample and 14.8% (95% CI, 12.2-17.4) for California. The overall incidence rate was 6.0/10,000 calls (95% CI, 3.9-8.1). These rates represent more than 49,000 total exposures and more than 10,000 needlesticks per year among paramedics in the United States. Rates for mucocutaneous exposures and needlesticks were similar (approximately 1.2/10,000 calls). Rates for California were one third to one half the national rates. Sensitivity analysis showed that potential response bias would have little impact on the policy and intervention implications of the findings. CONCLUSION: Paramedics continue to be at substantial risk for blood exposure. More attention should be given to reducing mucocutaneous exposures. The impact of legislation on reducing exposures and the importance of nonintact skin exposures need to be better understood.

Achieving universal HIV screening in prenatal care in the United States: provider persistence pays off.

Routine voluntary HIV testing with the right to decline (the "opt-out" approach) is recommended for all pregnant women in the United States but not all are tested. We examined data from surveys of prenatal care providers to identify factors associated with universal testing among patients. Data are from a probability survey conducted in 1999 with prenatal care providers in four separate areas. Survey participants completed a self-administered questionnaire. We computed the percentage of providers reporting universal testing by characteristics of the provider's practice, medical specialty, how strongly they encouraged testing, perceptions of patients' risk, and whether they saw patients in public clinics. In the four locations (Brooklyn, New York; North Carolina; Connecticut; and Dade County, Florida) 95%-99% of providers reported that they routinely offered HIV testing to all pregnant women; the average percentage tested was 64%-89%. The percentage reporting that all of their patients were tested ranged from 12%-62%. The percent of providers reporting universal testing was positively associated with the degree to which testing was encouraged, particularly encouragement to women perceived to be low risk. In some areas, universal testing varied by medical profession, with obstetric physicians and residents, and nurse-midwives reporting a lower percentage of universal testing than family practice physicians and residents. To achieve the goal of routine HIV testing of all pregnant women, education and training must be delivered to all prenatal care providers. This training should emphasize the importance of routine testing. Even with the opt-out approach, many women may decline testing if their doctor does not recommend and encourage HIV testing.

Safety climate and use of personal protective equipment and safety medical devices among home care and hospice nurses.

Use of personal protective equipment (PPE) and safety medical devices is mandated for healthcare workers to reduce the risk of infection with human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) from exposure to patients' blood. Research has shown that a strong safety climate may promote increased use of PPE. Therefore, the objective of this study was to examine the association between safety climate and use of PPE among homecare/hospice nurses in North Carolina. To this end, a mail survey was conducted in 2006. The response rate, adjusted on the assumption that the proportion of eligible nurses from among those who did not return the questionnaire or could not be contacted was similar to the proportion among those who did return the questionnaire, was 69% (n=833 eligibles). The percentage of nurses who used the specified PPE was two to three times greater among nurses who had a strong safety climate. Safety climate was only weakly associated with using safety devices. These results suggest that improving safety climate may be a powerful tool for increasing use of PPE.

Work experience, work environment, and blood exposure among home care and hospice nurses.

Blood exposure rates among home care and hospice nurses (RNs) in the United States are markedly lower for nurses with more home care/hospice experience, whether or not they have more total years of nursing experience (i.e., in other work environments). This study examined whether the protective effect of home care/hospice experience was greater for nurses who worked under three types of circumstances that are typical of the home care/hospice work environment and conducive to blood exposure. A mail survey was conducted in 2006 among home care/hospice nurses in North Carolina, a largely rural state in the southeastern U.S. The adjusted response rate was 69% (n=833). Blood exposure rates were higher among nurses with ≤5 years' experience in home care/hospice. Contrary to expectations, the protective effect of more experience was greater among nurses who did not have limited access to safety devices/personal protective equipment, did not have to rush during home visits, and did not often visit homes with unrestrained pets, unruly children, poor lighting, or extreme clutter. These results suggest that characteristics of the home care/hospice work environment limit nurses' ability to use their experience to prevent blood exposure.

Using formative research to design an epidemiologic survey: the north Carolina study of home care and hospice nurses.

OBJECTIVES: Formative research can serve as a means of obtaining important information for designing an epidemiologic study, but descriptions of this approach in the epidemiologic literature are lacking. The objective of this paper is to describe the use of three formative research techniques in designing a survey of home care and hospice nurses. METHODS: We conducted two focus groups, seven key informant interviews, and approximately fifteen hours of direct observation among home care and hospice nurses recruited by word of mouth in North Carolina in 2006. RESULTS: We used information obtained from the formative research to decide which survey design would likely be most successful with this population (mail survey, as opposed to Internet survey or in-person interviews), which measure to use for the denominator of the blood exposure incidence rates (number of visits, as opposed to patient-time), and which items and response options to include in the questionnaire, as well as to identify specific survey techniques that would likely increase the response rate (emphasizing the regional focus of the study; sending the questionnaire to the home address). CONCLUSION: When particular information for planning a study is unavailable from the literature or the investigator's experience, formative research can be an effective means of obtaining that information.

Provision and use of personal protective equipment among home care and hospice nurses in North Carolina.

BACKGROUND: We investigated the frequency with which home care/hospice nurses are provided with and use personal protective equipment (PPE) and factors associated with use. METHODS: We conducted a mail survey among home care/hospice nurses in North Carolina in 2006. RESULTS: The adjusted response rate was 69% (n = 833). Between 68% and 86% of nurses were always provided with the relevant types of PPE; these nurses were 2.5-3 times more likely to use the PPE in scenarios involving a potential for blood exposure compared with nurses who were not always provided with PPE. Nurses who always had sufficient time during home visits were 50% more likely to use PPE. Nurses who visited more homes with adverse working conditions were less likely to use PPE. CONCLUSION: The public health policy of providing PPE to health care workers and ensuring that they use that equipment to prevent occupational blood exposure is not being fully implemented for home care and hospice nurses. Greater provision of PPE could reduce blood exposure in this population. Conditions of the home care/hospice work environment may be impeding nurses' ability to use PPE.

Provision and use of safety-engineered medical devices among home care and hospice nurses in North Carolina.

BACKGROUND: Nurses who provide care in the home are at risk of blood exposure from needlesticks. Using safety-engineered medical devices reduces the risk of needlestick. The objectives of this study were to assess provision of safety devices by home care and hospice agencies as well as the use of these devices by home care and hospice nurses in North Carolina, and to examine the association between provision and use. METHODS: A mail survey was conducted among North Carolina home care and hospice nurses in 2006. RESULTS: The adjusted response rate was 69% (n = 833). The percentage of nurses who were always provided with safety devices ranged from 51% (blood tube holders) to 83% (winged steel needles). Ninety-five percent of nurses who were always provided with safety devices, but only 15%-50% of nurses who were not always provided with safety devices, used a safety device the last time they used that general type of device. Among nurses who did not use a safety device on that occasion, 60%-80% did not use it because it was not provided by the agency. CONCLUSION: This study suggests that limited access is the primary reason for home care/hospice nurses' failure to use safety devices. The policy goal of providing safety devices to health care workers in all situations in which such devices could reduce their risk of needlestick is not being achieved for home care nurses in North Carolina.

U.S. Maternally linked birth records may be biased for Hispanics and other population groups.

PURPOSE: We sought to advance understanding of linkage error in U.S. maternally linked datasets and how the error might affect results of studies based on the linked data. METHODS: North Carolina birth and fetal death records for 1988-1997 were maternally linked (n=1,030,029). The maternal set probability, defined as the probability that all records assigned to the same maternal set do in fact represent events to the same woman, was used to assess differential maternal linkage error across race/ethnic groups. RESULTS: Maternal set probabilities were lower for records specifying Asian or Hispanic race/ethnicity, suggesting greater maternal linkage error for these sets. The lower probabilities for Hispanics were concentrated in women of Mexican origin who were not born in the United States. CONCLUSIONS: Differential linkage error may be a source of bias in studies that use U.S. maternally linked datasets to make comparisons between Hispanics and other groups or among Hispanic subgroups. Methods to quantify and adjust for this potential bias are needed.

Management practices and risk of occupational blood exposure in U.S. paramedics: non-intact skin exposure.

PURPOSE: To estimate the risk of blood exposure to non-intact skin in U.S. paramedics; to estimate risk ratios for selected management practices. METHODS: A mail survey was conducted among a national sample of licensed paramedics in the United States in 2002-2003. RESULTS: The adjusted response rate was 55% (N = 2,664). The overall 12-month risk of non-intact skin blood exposure was 8.7% (95% confidence interval: 6.4-11). As the number of types of personal protective equipment (PPE) always provided by the employer increased, risk decreased. Risk ratios and 95% confidence intervals for selected factors were: not being provided with appropriate PPE, 2.4 (1.6-3.3); job evaluation doesn't include following safety procedures, 1.8 (1.0-2.7); supervisor wouldn't speak to paramedic about not following Universal Precautions, 2.1 (0.9-3.2); both of the above supervisory behaviors, 2.3 (1.3-3.6). CONCLUSIONS: Providing appropriate personal protective equipment is an effective means of preventing non-intact skin blood exposure and possible consequent bloodborne infection in paramedics. Future research should aim to identify factors limiting the provision of this equipment and to evaluate the advisability of interventions to increase provision. Supervisory behaviors that emphasize safe work practices may also be effective in preventing non-intact skin exposure in paramedics. Future research should develop interventions that apply general knowledge of management behaviors that promote worker safety to the work environment of paramedics.

Documentation of incidental factors affecting the home healthcare work environment.

Working conditions related to unrestrained pets, unruly children, clutter, and poor lighting during home healthcare visits are considered normal aspects of care providers' jobs. To date, there has been no documentation related to how often these factors are present in the home healthcare setting during home visits. In this study, 833 home healthcare nurses practicing in North Carolina answered a questionnaire that included items related to how often unrestrained pets, unruly children, poor lighting, and clutter existed in the homes they visited. Results showed that one-third to one-half of the respondents usually or always visited homes with unrestrained pets, clutter, or poor lighting and few nurses usually or always visited homes with uncontrolled children. Better understanding of the prevalence of these factors will facilitate further study related to their effects on safety, efficiency, and job satisfaction for home healthcare workers.

Circumstances surrounding occupational blood exposure events in the National Study to Prevent Blood Exposure in Paramedics.

More than 20% of U.S. paramedics are exposed to blood each year. Little is known about the circumstances that lead to these exposures. The objective of this study was to describe blood exposure events among U.S. paramedics. A mail survey was conducted in 2002-2003 among a nationally representative sample of licensed paramedics. Eighty percent of needle/lancet sticks involved non-safety devices. A third of mucous membrane exposures occurred even though the paramedic was wearing eye or face protection; in half of the events, the exposures were caused by the patient vomiting, spitting, or coughing up blood; in a third of the events, the patient was being uncooperative or combative. In 83% of the non-intact skin exposures, the paramedic was wearing disposable gloves; the non-intact skin was covered before the call in a third of the events, but the cover did not prevent exposure; 40% of the events occurred when the patient was being uncooperative or combative. These results suggest that blood exposure among paramedics could be reduced through increased use of safety devices and personal protective equipment, improved engineering and design, and increased compliance with Universal Precautions, and that paramedics need techniques for avoiding blood exposure while treating uncooperative or combative patients.

The national study to prevent blood exposure in paramedics: exposure reporting.

BACKGROUND: This survey was conducted to provide national incidence rates and risk factors for exposure to blood among paramedics. The present analysis assesses reporting of exposures to employers. METHODS: A questionnaire was mailed in 2002-2003 to a national sample of paramedics selected using a two-stage design. Information on exposure reporting was obtained on the two most recent exposures for each of five routes of exposure. RESULTS: Forty-nine percent of all exposures to blood and 72% of needlesticks were reported to employers. The main reason for under-reporting was not considering the exposure a "significant risk." Females reported significantly more total exposures than males. Reporting of needlesticks was significantly less common among respondents who believed most needlesticks were due to circumstances under the worker's control. Reporting was non-significantly more common among workers who believed reporting exposures helps management prevent future exposures. Reporting may have been positively associated with workplace safety culture. CONCLUSIONS: This survey indicates there is need to improve the reporting of blood exposures by paramedics to their employers, and more work is needed to understand the reasons for under-reporting. Gender, safety culture, perception of risk, and other personal attitudes may all affect reporting behavior.

Provision and use of personal protective equipment and safety devices in the National Study to Prevent Blood Exposure in Paramedics.

BACKGROUND: Paramedics are at risk for human immunodeficiency virus, hepatitis B virus, and hepatitis C virus infection from occupational blood exposure. This study examined how often paramedics are provided with personal protective equipment (PPE), sharps containers, and selected safety devices by their employers; the frequency with which paramedics use sharps containers and these safety devices; and paramedics' attitudes regarding this equipment. METHODS: We conducted a mail survey among a nationally representative sample of certified paramedics. California was oversampled to allow for separate estimation of proportions for this population. RESULTS: The final sample included 2588 paramedics, 720 of whom were from California (adjusted response rate, 55%). Paramedics in California were provided safety devices more often than paramedics in the United States as a whole. For each type of device, there was at least a 40% increase in use when the device was always provided compared with when it was not always provided. Eighty-four percent of paramedics thought that safety needles significantly reduce blood exposure, but substantial percentages thought that safety needles, eye protection, and masks interfere with some medical procedures. Approximately one fifth said that they need more training in the use of safety devices and PPE. CONCLUSION: Lack of access to safety devices is the major barrier to their use, and the higher rates of provision and use in California may be the result of the state's early safety needle legislation. Increased provision, training, and improvement of safety equipment are needed to better protect paramedics from blood exposure.

A new method for measuring misclassification of maternal sets in maternally linked birth records: true and false linkage proportions.

OBJECTIVES: Numerous studies have used maternally linked birth records to investigate perinatal outcomes, maternal behaviors, and the quality of vital records birth data. Little attention has been given to assessing errors in the linkages and to understanding how such errors affect estimates derived from the linked data. The author developed a framework for conceptualizing maternal linkage error and measures for quantifying it, and examined the behavior of the new measures in a maternally linked file. METHODS: Linkage errors were conceptualized as misclassification, with the classes being the maternal sets (records classified as representing different births to the same woman). The true linkage proportion, analogous to sensitivity, was used to capture the degree to which all of a woman's births were assigned to a single maternal set; the false linkage proportion, analogous to specificity, was used to capture the degree to which the assigned maternal sets combined births from different women. The behavior of the two proportions was examined by introducing increasing degrees of linkage error into a maternally linked file. RESULTS: Both measures indicated greater misclassification with increasing simulated linkage errors. CONCLUSIONS: The new measures may be a useful tool for assessing the quality of maternally linked data, as well as other types of linked records where the linkages are within a single file. This is a necessary step towards developing methods for addressing misclassification bias in studies of maternally linked records through sensitivity analysis, adjustment, and other means.