Improving public health surveillance using a dual-frame survey of landline and cell phone numbers.

To meet challenges arising from increasing rates of noncoverage in US landline-based telephone samples due to cell-phone-only households, the Behavioral Risk Factor Surveillance System (BRFSS) expanded a traditional landline-based random digit dialing survey to a dual-frame survey of landline and cell phone numbers. In 2008, a survey of adults with cell phones only was conducted in parallel with an ongoing landline-based health survey in 18 states. The authors used the optimal approach to allocate samples into landline and cell-phone-only strata and used a new approach to weighting state-level landline and cell phone samples. They developed logistic models for each of 16 health indicators to examine whether exclusion of adults with cell phones only affected estimates after adjustment for demographic characteristics. The extents of the potential biases in landline telephone surveys that exclude cell phones were estimated. Biases resulting from exclusion of adults with cell phones only from the landline-based survey were found for 9 out of the 16 health indicators. Because landline noncoverage rates for adults with cell phones only continue to increase, these biases are likely to increase. Use of a dual-frame survey of landline and cell phone numbers assisted the BRFSS efforts in obtaining valid, reliable, and representative data.

Safety of Psychiatric Inpatients at the Veterans Health Administration.

OBJECTIVE: Although reducing adverse events and medical errors has become a central focus of the U.S. health care system over the past two decades both within and outside the Veterans Health Administration (VHA) hospital systems, patients treated in psychiatric units of acute care general hospitals have been excluded from major research in this field. METHODS: The study included a random sample of 40 psychiatric units from medical centers in the national VHA system. Standardized abstraction tools were used to assess the electronic health records from 8,005 hospitalizations. Medical record administrators screened the records for the presence of ten specific types of patient safety events, which, when present, were evaluated by physician reviewers to assess whether the event was the result of an error, whether it caused harm, and whether it was preventable. RESULTS: Approximately one in five patients experienced a patient safety event. The most frequently occurring events were medication errors (which include delayed and missed doses) (17.2%), followed by adverse drug events (4.1%), falls (2.8%), and assault (1.0%). Most patient safety events (94.9%) resulted in little harm or no harm, and more than half (56.6%) of the events were deemed preventable. CONCLUSIONS: Although patient safety events in VHA psychiatric inpatient units were relatively common, a great majority of these events resulted in little or no patient harm. Nevertheless, many were preventable, and the study provides data with which to target future initiatives that may improve the safety of this vulnerable patient population.

Estimating the prevalence of uninsured children: an evaluation of data from the National Survey of Children with Special Health Care Needs, 2001. Data evaluation and methods research.

UNLABELLED: The National Survey of Children with Special Health Care Needs revealed that 8.3% of children under 18 years of age were uninsured, a rate lower than the rate estimated by other national surveys. This report presents the results of an evaluation of the quality of this estimate, based on analyses of non-response, question design, interviewer and respondent effects, and the weighing and estimation process. National and State-level statistics on health insurance coverage for children with special health care needs (CSHCN) and for children without special needs are included in an appendix. SOURCE OF DATA: The National Survey of CSHCN is a survey module of the State and Local Area Integrated Telephone Survey. This survey of parents and guardians collected health insurance coverage information for a national sample of 215, 162 children. Data were collected from October 2000 through April 2002. RESULTS: Compared with other surveys, weighted data from the National Survey of CSHCN describe a population with a slightly larger proportion of Hispanic children and children from households with higher incomes. The National Survey of CSHCN was also the only survey to use a child-level design: A randomized experiment that varied the health insurance questions found that repeating the coverage questions for each child produced lower unisurance rates than household-level questions that first asked if anyone in the househol was insured. CONCLUSION: Question design differences explain much of the discrepancy between survey estimates of the uninsurance rate, but a definitive conclusion regarding the relative accuracy of the uninsurance rates is not possible.

When data are not missing at random: implications for measuring health conditions in the Behavioral Risk Factor Surveillance System.

OBJECTIVES: To examine the effect on estimated levels of health conditions produced from large-scale surveys, when either list-wise respondent deletion or standard demographic item-level imputation is employed. To assess the degree to which further bias reduction results from the inclusion of correlated ancillary variables in the item imputation process. DESIGN: Large cross-sectional (US level) household survey. PARTICIPANTS: 218 726 US adults (18 years and older) in the 2006 Behavioral Risk Factor Surveillance System Survey. This survey is the largest US telephone survey conducted by the Centers for Disease Control and Prevention. PRIMARY AND SECONDARY OUTCOME MEASURES: Estimated rates of severe depression among US adults. RESULTS: The use of list-wise respondent deletion and/or demographic imputation results in the underestimation of severe depression among adults in the USA. List-wise deletion produces underestimates of 9% (8.7% vs 9.5%). Demographic imputation produces underestimates of 7% (8.9% vs 9.5%). Both of these differences are significant at the 0.05 level. CONCLUSION: The use of list-wise deletion and/or demographic-only imputation may produce significant distortion in estimating national levels of certain health conditions.

A probability sample for monitoring the HIV-infected population in care in the U.S. and in selected states.

Epidemiologic and clinical changes in the HIV epidemic over time have presented a challenge to public health surveillance to monitor behavioral and clinical factors that affect disease progression and HIV transmission. The Medical Monitoring Project (MMP) is a supplemental surveillance project designed to provide representative, population-based data on clinical status, care, outcomes, and behaviors of HIV-infected persons receiving care at the national level. We describe a three-stage probability sampling method that provides both nationally and state-level representative estimates.In stage-I, 20 states, which included 6 separately funded cities/counties, were selected using probability proportional to size (PPS) sampling. PPS sampling was also used in stage-II to select facilities for participation in each of the 26 funded areas. In stage-III, patients were randomly selected from sampled facilities in a manner that maximized the possibility of having overall equal selection probabilities for every patient in the state or city/county. The sampling methods for MMP could be adapted to other research projects at national or sub-national levels to monitor populations of interest or evaluate outcomes and care for a range of specific diseases or conditions.

Design and operation of the National Asthma Survey.

OBJECTIVES: This report presents detailed information on the National Asthma Survey (NAS), a module of the State and Local Area Integrated Survey program conducted by the Centers for Disease Control and Prevention's (CDC) National Center for Health Statistics. NAS, sponsored by the CDC's National Center for Environmental Health, was designed to produce national prevalence estimates of adults and children with asthma; to describe the health, socioeconomic, behavioral, and environmental predictors that relate to controlling asthma better; and to characterize the content of care and limitations of persons with asthma. National prevalence estimates were constructed to be consistent with those produced from the CDC's National Health Interview Survey (NHIS), although prevalence estimates for subpopulations may or may not be consistent with NHIS. METHODS: Two separate random-digit-dial telephone studies were fielded: a national study and a four-state study in Alabama, California, Illinois, and Texas. Children aged 0-17 years and adults aged 18 years and over were included in both studies. The screening procedure differed between the studies. Percentages can be generated for the four states combined or for each state separately. A substudy was conducted in the national study to examine the accuracy of proxy reports of asthma. RESULTS: Data were collected from February 2003 to March 2004. A total of 955 detailed asthma interviews were completed in the national study and 5,741 in the four-state study. A data file has been released for each study that contains asthma, health, and demographic data, as well as sampling weights. The weighted overall response rates were 47.2% for the national sample and 48.5% for the four-state sample.

Address-based versus random-digit-dial surveys: comparison of key health and risk indicators.

Use of random-digit dialing (RDD) for conducting health surveys is increasingly problematic because of declining participation rates and eroding frame coverage. Alternative survey modes and sampling frames may improve response rates and increase the validity of survey estimates. In a 2005 pilot study conducted in six states as part of the Behavioral Risk Factor Surveillance System, the authors administered a mail survey to selected household members sampled from addresses in a US Postal Service database. The authors compared estimates based on data from the completed mail surveys (n = 3,010) with those from the Behavioral Risk Factor Surveillance System telephone surveys (n = 18,780). The mail survey data appeared reasonably complete, and estimates based on data from the two survey modes were largely equivalent. Differences found, such as differences in the estimated prevalences of binge drinking (mail = 20.3%, telephone = 13.1%) or behaviors linked to human immunodeficiency virus transmission (mail = 7.1%, telephone = 4.2%), were consistent with previous research showing that, for questions about sensitive behaviors, self-administered surveys generally produce higher estimates than interviewer-administered surveys. The mail survey also provided access to cell-phone-only households and households without telephones, which cannot be reached by means of standard RDD surveys.

Design and Operation of the National Survey of Children's Health, 2003.

Objectives-This report presents the development, plan, and operation of the National Survey of Children's Health(NSCH), a module of the State and Local Area Integrated Telephone Survey, conducted by the Centers for Disease Control and Prevention's(CDC) National Center for Health Statistics. This survey was designed to produce national and State-specific prevalence estimates for a variety of physical, emotional, and behavioral health indicators and measures of children's experiences with the health care system. The survey also includes questions about the family (e.g., parents' health status, stress and coping behaviors, family activities) and about respondents' perceptions of the neighborhoods where their children live. Primary funding for this survey was provided by the Maternal and Child Health Bureau, Health Resources and Services Administration. Additional support was received from the CDC's National Center for Infectious Diseases, using funds provided by the National Vaccine Program Office. Methods-A random-digit-dial sample of households with children under 18 years of age was selected from each of the 50 States and the District of Columbia. One child was randomly selected from all children in each identified household to be the subject of the survey. The respondent was the parent or guardian who knew the most about the child's health and health care. Results-A total of 102,353 interviews were completed from January 2003 to July 2004. The weighted overall response rate was 55.3%. A data file has been released that contains demographic information on the selected child, substantive health and well-being data for the child and his/her family, and sampling weights. Estimates based on the sampling weights generalize to the noninstitutionalized population of children in each State and nationwide.

Adjustments for non-telephone bias in random-digit-dialling surveys.

Telephone surveys are widely used in the U.S.A. for the study of health-related topics. They are subject to 'coverage bias' because they cannot sample households that do not have telephones. Although only around 5 per cent of households do not have a telephone, rates of telephone coverage show substantial variation by geography, demographic factors and socio-economic factors. In particular, lack of telephone service is more common among households that contain ethnic and racial minorities or that have lower socio-economic status with fewer opportunities for access to medical care and poorer health outcomes. Thus, failure to adequately account for households without telephones in health surveys may yield estimates of health outcomes that are misleading, particularly in states with at least moderate telephone non-coverage. The dynamic nature of the population of households without telephones offers a way of accounting for such households in telephone surveys. At any given time the population of telephone households includes households that have had a break or interruption in telephone service. Empirical results strongly suggest that these households are very similar to households that have never had telephone service. Thus, sampled households that report having had an interruption in telephone service may be used also to represent the portion of the population that has never had telephone service. This strategy can lead to a reduction in non-coverage bias in random-digit-dialling surveys. This paper presents two methods of adjusting for non-coverage of non-telephone households. The effectiveness of these methods is examined using data from the National Health Interview Survey. The interruption-in-telephone-service methods reduce non-coverage bias and can also result in a lower mean squared error. The application of the interruption-in-telephone-service methods to the National Immunization Survey is also discussed. This survey produces estimates for the 50 states and 28 urban areas. The interruption-in-telephone-service estimates tend be slightly lower than estimates resulting from poststratification and from another non-coverage adjustment method. The results suggest that the reduction in bias is greatest for variables that are highly correlated with the presence or absence of telephone service.