Tracing 8,600 participants 36 years after recruitment at age seven for the Tasmanian Asthma Study

OBJECTIVE: To trace all participants 36 years after the original Tasmanian Asthma Study (TAS). METHODS: In 1968, the TAS investigated asthma in 8,583 children who were born in 1961. We attempted to trace these participants in 2002-04 using names, dates of birth and gender. Current addresses were sought by computer linkage to the Commonwealth Electoral Roll, the Medicare database and the Tasmanian marriage records. Computer linkage was conducted with the National Death Index (NDI). Siblings of participants were also linked to the Commonwealth Electoral Roll and those identified were sent a letter requesting the participant's address. The Australian Twin Registry (ATR) and the 1991-93 TAS substudy were used to locate participant addresses. RESULTS: After three rounds of electoral roll linkage, 56% of all cohort members were traced. Name changes were identified for 49% of the 3,477 females not initially matched to the electoral roll using linkage to marriage records. NDI linkage yielded a 0.7% match. Medicare linkage identified addresses for 27% of the 1,982 remaining participants. Writing to siblings located 60% of 1,661 participants. One hundred and eighty-three participants were matched to the 1991-93 TAS and 23 twins matched to the ATR. Overall, 81.5% of the cohort members were identified. CONCLUSIONS: With these methods, we have been able to trace a possible address for a large portion of the original participants, with the electoral roll linkage being the most useful. IMPLICATIONS: It is possible to trace Australians for follow-up studies using electronic linkage, although without unique identifiers it is labour and resource intensive and requires matching to several databases.     

Case definition in epidemiologic studies of AD/HD

PURPOSE: Propose a five-step multigating, multimodal procedure for research case definition and identification of attention-deficit/hyperactivity disorder (AD/HD) in population-based epidemiologic studies. METHODS: Subjects included a birth cohort of all children born between 1976 and 1982 who remained in Rochester after age 5. Screening for AD/HD required 4 steps, using these sources: school/medical records, computerized diagnostic index, and private psychiatry records. In step 5, research criteria were applied to potential cases. The model for defining cases used combinations of three categories of information (DSM-IV, questionnaire, clinical diagnosis). Validity was tested by comparing medication treatment, substance abuse, school outcomes, and comorbidities between cases who did or did not meet DSM-IV criteria. RESULTS: Among 5718 subjects, 1344 potential cases were identified; 379 met research criteria. No difference in gender, treatment, school outcome, or professional making clinical diagnoses was found between cases who did (N=228) and did not (N=151) meet DSM-IV criteria. However, cases not meeting DSM-IV criteria were more inattentive (33.8% vs. 17.1%; p < 0.001), older (age 12.8 vs. 10.5 years; p=0.01), with less substance abuse (15.2% vs. 26.3%; p < 0.001) and psychiatric comorbidities (43.1% vs. 54.4%; p=0.031). CONCLUSIONS: If only DSM-IV criteria were applied, 151 cases would not have been identified. This study underscores the importance of using multiple sources and combinations of documented information for case definition and identification.     

An intergenerational and lifecourse study of health and mortality risk in parents of the 1958 birth cohort: (I) methods and tracing

OBJECTIVES: This paper describes the methods used to obtain information on mortality and cancer registrations for the parents of the British 1958 birth cohort, in order to create a dataset that can be used to examine intergenerational relationships on health and growth. STUDY DESIGN: Intergenerational cohort study. METHODS: The 1958 cohort includes all births occurring during 1 week in March 1958 in England, Scotland and Wales. For more than four decades of follow-up, information has been collected on cohort members, their parents and children. Information on the National Health Service (NHS) numbers of the parents was not available, but other details were collated for the Office for National Statistics to trace and flag the biological parents of the cohort members. RESULTS: Tracing was successful in 90.2% of fathers (n = 14,334) and 94.9% of mothers (n = 15,076). The greatest success was achieved for parents in families where there was no indication for additional mother or father figures until the child was 16 years old (96.6% of the mothers traced, n = 14,274; 94.3% of the fathers traced, n = 13,256). Tracing rates were lower than average in unmarried mothers (59%) and for the small group who were separated, widowed or divorced in 1958 (81%); the rates were particularly poor for the corresponding fathers (24.4 and 54.7%, respectively). There were only small variations in tracing rates between different regions of Britain. CONCLUSIONS: The tracing rates achieved were generally very high despite the lack of NHS number, especially where there was family stability throughout the childhood of cohort members. Parental status will need to be considered in future studies. With the high tracing rates achieved, the dataset provides an important resource with which to evaluate multigenerational associations with health and development in parents, their offspring and grandchildren.     

Using multiple information sources to identify opportunities for ergonomic interventions in automotive parts distribution: a case study

An essential activity in any ergonomics program is determining specific work locations and activities where physical demands place workers at increased risk of sustaining an overexertion injury. To do this, safety and health professionals rely on a variety of information sources to identify and prioritize opportunities for ergonomic interventions. As part of a 4-year project to reduce overexertion injuries in the service parts division of a major auto maker, a study was performed in 19 parts distribution centers to evaluate the contributions of the following information sources in identifying specific high-risk work locations and activities: (1) archival medical/injury records, (2) identification of "problem tasks" by plant-based ergonomic committees, (3) facility walk-throughs by experienced ergonomists, and (4) detailed ergonomic job analyses. Archival records were not particularly useful in identifying high-risk activities because essential exposure information (e.g., task, work location) was not documented. Walk-throughs and detailed ergonomic analyses were partially effective in identifying high-risk activities; however, in some cases the observation time was too short to observe peak exposures. Ergonomic committees were generally effective in identifying specific high-risk tasks and work locations. Rankings of "problem tasks" from multiple sites identified consensus division-wide ergonomic concerns. Detailed ergonomic job analyses confirmed that these tasks had high exposure to ergonomic risk factors. This study demonstrated potential pitfalls in relying on a single information source to identify work locations and activities that place workers at increased risk of overexertion injury.     

Ability to trace migrant farmworkers ten years after initial identification in a Northern State (Wisconsin).

BACKGROUND: Migrant farmworkers have rarely been included in epidemiologic studies. To assess the feasibility of following farmworkers over extended periods, a critical feature of many study designs, we attempted to trace a sample of Mexican-American farmworkers identified in a clinic in Wisconsin. METHODS: We randomly chose 100 farmworkers from a migrant health center registration list for 1984-85. In 1995, we searched recent clinic records, made telephone calls, and visited migrant camps to find these farmworkers in Wisconsin during the growing season. We also attempted to find 46 farmworkers at their homes in southwest Texas over a two-week period in 1996 using the address listed in the clinic records, local phone books, and conversations with next-door neighbors. RESULTS: Although 25 farmworkers had reregistered at the clinic in recent years, we found only 6 of them in Wisconsin in 1995. In southwest Texas, we either located or ascertained information about the vital status of 25 of the 46 farmworkers (54%). CONCLUSIONS: Tracing efforts must include extensive contacts in farmworkers' home states and must incorporate a variety of information sources. Tracing farmworkers in epidemiologic studies appears to be feasible but requires more intensive methods over longer periods of time than those used in this study.     

Identification of an industrial cohort and verification of its completeness using a complicated system of plant records

The published literature on occupational mortality studies seldom describes the manner in which cohorts were assembled and efforts made to ensure that all, or nearly all, eligible persons had been enumerated. Researchers must struggle unassisted through a morass of plant records, often not knowing how to utilize important sources of information to the fullest extent. This paper describes the identification of a cohort of over 8,700 foundry workers and the verification of its completeness using existing plant data sources. By understanding the techniques for manipulating data sources in this investigation, researchers may gain insight into the use of materials available to them.     

Follow-up methods for retrospective cohort studies in New Zealand

Objectives: To define a general methodology for maximising the success of follow-up processes for retrospective cohort studies in New Zealand, and to illustrate an approach to developing country-specific follow-up methodologies.
Methods: We recently conducted a cohort study of mortality and cancer incidence in New Zealand professional fire fighters. A number of methods were used to trace vital status, including matching with records of the New Zealand Health Information Service (NZHIS), pension records of Work and Income New Zealand (WINZ), and electronic electoral rolls. Non-electronic methods included use of paper electoral rolls and the records of the Registrar of Births Deaths and Marriages.
Results: 95% of the theoretical person-years of follow-up of the cohort were traced using these methods. In terms of numbers of cohort members traced to end of follow-up, the most useful tracing methods were fire fighter employment records, the NZHIS, WINZ, and the electronic electoral rolls.
Conclusions: The follow-up process used for the cohort study was highly successful. On the basis of this experience, we propose a generic, but flexible, model for follow-up of retrospective cohort studies in New Zealand. Similar models could be constructed for other countries.
Implications: Successful follow-up of cohort studies is possible in New Zealand using established methods. This should encourage the use of cohort studies for the investigation of epidemiological issues. Similar models for follow-up processes could be constructed for other countries.     

Follow-up methods for retrospective cohort studies in New Zealand

OBJECTIVES: To define a general methodology for maximising the success of follow-up processes for retrospective cohort studies in New Zealand, and to illustrate an approach to developing country-specific follow-up methodologies. METHODS: We recently conducted a cohort study of mortality and cancer incidence in New Zealand professional fire fighters. A number of methods were used to trace vital status, including matching with records of the New Zealand Health Information Service (NZHIS), pension records of Work and Income New Zealand (WINZ), and electronic electoral rolls. Non-electronic methods included use of paper electoral rolls and the records of the Registrar of Births Deaths and Marriages. RESULTS: 95% of the theoretical person-years of follow-up of the cohort were traced using these methods. In terms of numbers of cohort members traced to end of follow-up, the most useful tracing methods were fire fighter employment records, the NZHIS, WINZ, and the electronic electoral rolls. CONCLUSIONS: The follow-up process used for the cohort study was highly successful. On the basis of this experience, we propose a generic, but flexible, model for follow-up of retrospective cohort studies in New Zealand. Similar models could be constructed for other countries. IMPLICATIONS: Successful follow-up of cohort studies is possible in New Zealand using established methods. This should encourage the use of cohort studies for the investigation of epidemiological issues. Similar models for follow-up processes could be constructed for other countries.     

Administrative databases provide inaccurate data for surveillance of long-term central venous catheter-associated infections.

BACKGROUND: Efficient methods are needed to monitor infections associated with long-term central venous catheters (CVCs) in both inpatient and outpatient settings. Automated medical records and claims data have been used for surveillance of these infections without evaluation of their accuracy or validity. OBJECTIVE: To determine the feasibility of using electronic records to identify CVC placement and design a system for identifying CVC-associated infections. DESIGN AND SETTING: Retrospective cohort study at an HMO and two teaching hospitals in Boston, one adult (hospital A) and one pediatric (hospital B), between January 1991 and December 1997. Tunneled catheters, totally implanted catheters, and hemodialysis catheters were examined. Claims databases of both the HMO and the hospitals were searched for 10 CPT codes, 2 ICD-9 codes, and internal charge codes indicating CVC insertion. Lists were compared with each other and with medical records for correlation and accuracy. PATIENTS: All members of the HMO who had a CVC inserted at one of the two hospitals during the study period. RESULTS: There was wide variation in the CVC insertions identified in each database. Although ICD-9 codes at each hospital and CPT/ICD-9 combinations at the HMO found similar total numbers of CVCs, there was little overlap between the individuals identified (62% for hospital A with HMO and 4% for hospital B). CONCLUSION: Claims data from different sources do not identify the same CVC insertion procedures. Current administrative databases are not ready to be used for electronic surveillance of CVC-associated complications without extensive modification and validation.     

Value of mortality data and necropsy records in monitoring morbidity in a population.

STUDY OBJECTIVE--The aim was to compare the value of four sources of data in assessing morbidity in a population: (1) data from a screening programme including follow up records, (2) death certifications by attending physicians, (3) death certifications by doctor-coroners, and (4) necropsy reports. DESIGN--The study was a cohort analysis of health and mortality in a sample of agricultural workers first examined in 1964-66 when they were aged 60 years or older. Follow up examinations enabled morbidity assessment to be made and ICD diagnostic categories to be compared with data available on persons in the cohort who had died. SETTING--Hajdúszoboszló, a small town in eastern Hungary. PARTICIPANTS--1412 persons (96.1% of those aged greater than or equal to 60 years) were examined in 1964-6. Those still alive and available in 1989 were examined again. Necropsy records were available for 144 persons from the cohort in 1989 and were extensively reviewed in comparison with data available from other sources. MEASUREMENTS AND MAIN RESULTS--Comparison of causes of death established at necropsy showed marked differences from those registered by attending physicians and doctor-coroners, deviations ranging from -91.6% to +74.8%; 19.4% of underlying causes of death occurred exclusively in the necropsy group. Major divergencies in diagnostic classification occurred in the three data sources, particularly for diseases of the circulatory system, where hypertensive renal disease, old myocardial infarction, acute cerebrovascular disease, and venous thrombosis were rarely documented by physicians/coroners. When necropsy data were used the number of diagnostic categories increased strikingly over the other sources of information. Necropsy records revealed quantitatively similar information on morbidity to follow up examination though there were qualitative differences, necropsy being less likely to document diagnoses of endocrine disorders, mental and neurological diseases, digestive disorders, and musculosketal disorders. CONCLUSIONS--Necropsy records contain much valuable material not available from other sources, exceeding by ninefold the amount of information reported at present. A way should be found to make use of this large data pool.     

医院之间信息共享的实现方案

目的：在医院之间实现影像类和非影像类患者的信息共享。方法：医院之间通过光纤连接，并设置中心索引服务器，将病历资料的索引信息保存在中心索引服务器。在需要查询时，通过检索中心索引服务器，确定病历资料所在服务器的位置．再从该服务器调阅患者资料。结果：在医院之间实现了患者的信息共享。结论：医院之间通过光纤连接，通过中心索引服务器，实现患者信息共享是一个可行的方案。     

The Hanford Thyroid Disease Study: an alternative view of the findings

The Hanford Thyroid Disease Study (HTDS) is one of the largest and most complex epidemiologic studies of the relation between environmental exposures to I and thyroid disease. The study detected no dose-response relation using a 0.05 level for statistical significance. The results for thyroid cancer appear inconsistent with those from other studies of populations with similar exposures, and either reflect inadequate statistical power, bias, or unique relations between exposure and disease risk. In this paper, we explore these possibilities, and present evidence that the HTDS statistical power was inadequate due to complex uncertainties associated with the mathematical models and assumptions used to reconstruct individual doses. We conclude that, at the very least, the confidence intervals reported by the HTDS for thyroid cancer and other thyroid diseases are too narrow because they fail to reflect key uncertainties in the measurement-error structure. We recommend that the HTDS results be interpreted as inconclusive rather than as evidence for little or no disease risk from Hanford exposures.     

Agreement between company-recorded and self-reported estimates of duration and frequency of occupational fumigant exposure

Investigators must often rely on self-reported work history information collected with questionnaires. However, little is known about the agreement between self-reported estimates of exposure and records kept by companies. As part of a cross-sectional medical study of structural fumigation workers, self-reported work history information was collected on both duration and frequency of exposure using an interviewer-administered questionnaire. All company records available on these workers were also collected. Only 15 of 81 structural fumigation companies identified by study participants as current or past structural fumigation employers had records suitable for comparison. These 15 companies employed 32 of the workers who participated in the cross-sectional medical study. The exposure information provided by the 32 workers was compared to information obtained from company records. By examining the agreement between these two data sources, potential limitations were identified in both the self-reported and company-recorded exposure data. By recognizing these limitations in the exposure data, we identified the most appropriate exposure measures to be used in subsequent data analyses. This exercise also demonstrated the difficulties in undertaking these exposure comparisons in an industry consisting of many small, independent companies. Similar difficulties with assessing exposures may be experienced by investigators studying other service industries consisting of many small, independent companies (e.g., dry cleaning, auto repair). Am. J. Ind. Med. 32:364–368, 1997. © 1997 Wiley-Liss, Inc.     

Variability in date of prostate cancer diagnosis: a comparison of cancer registry,pathology report,and electronic health data sources

PurposeThe date of cancer diagnosis is a critical data element for clinical care and research. Because this date can be abstracted from various data sources, its comparability from source to source is unclear. This study compared the date of diagnosis from multiple sources within the same population of prostate cancer patients.MethodsWe linked cancer registry, pathology report, and electronic health data sources from the Kaiser Permanente Southern California health data systems for a cohort of 22,666 members diagnosed with prostate cancer between 2000 and 2010. The magnitude and direction of the differences in date of diagnosis were assessed for each date pairwise comparison. We reviewed 454 medical records to determine reasons for date discrepancies.ResultsAmong the date pairwise comparisons, differences in date of diagnosis spanned from 9.6 years earlier to 10 years later than each other. However, the overall median difference ranged from 1 to 16 days, thus suggesting that the vast majority of the date differences were small. Chart review results identified major categories of date discrepancies.ConclusionsThese data demonstrate variability in date of diagnosis across these data sources. This variability may have implications for epidemiologic estimates or patient identification in research studies using different data sources.     

Arsenic in drinking-water and risk for cancer in Denmark

BACKGROUND: Arsenic is a well-known carcinogen, which is often found in drinking-water. Epidemiologic studies have shown increased cancer risks among individuals exposed to high concentrations of arsenic in drinking-water, whereas studies of the carcinogenic effect of low doses have had inconsistent results. OBJECTIVE: Our aim was to determine if exposure to low levels of arsenic in drinking-water in Denmark is associated with an increased risk for cancer. METHODS: The study was based on a prospective Danish cohort of 57,053 persons in the Copenhagen and Aarhus areas. Cancer cases were identified in the Danish Cancer Registry, and the Danish civil registration system was used to trace and geocode residential addresses of the cohort members. We used a geographic information system to link addresses with water supply areas, then estimated individual exposure to arsenic using residential addresses back to 1970. Average exposure for the cohort ranged between 0.05 and 25.3 microg/L (mean = 1.2 microg/L). Cox's regression models were used to analyze possible relationships between arsenic and cancer. RESULTS: We found no significant association between exposure to arsenic and risk for cancers of the lung, bladder, liver, kidney, prostate, or colorectum, or melanoma skin cancer; however, the risk for non-melanoma skin cancer decreased with increasing exposure (incidence rate ratio = 0.88/microg/L average exposure; 95% confidence interval, 0.84-0.94). Results adjusted for enrollment area showed no association with non-melanoma skin cancer. CONCLUSIONS: The results indicate that exposure to low doses of arsenic might be associated with a reduced risk for skin cancer.     

Validation of self diagnosis of high blood pressure in a sample of the Spanish EPIC cohort: overall agreement and predictive values. EPIC Group of Spain

STUDY OBJECTIVE: High blood pressure is a variable related to several chronic conditions whose repeated measurement in large cohort studies is often not feasible having to rely on the self reporting of the subjects. The aim of the study is to validate such self diagnosis in a sample of members from the Spanish EPIC cohort study. DESIGN: Comparison of high blood pressure self diagnosis with the information provided by the personal medical record drawn from the primary health centre of reference for such population. SETTING: A small town near the EPIC-Murcia centre, one of five Spanish EPIC centres located in the south east, where inclusion in the cohort was offered to the general population. PARTICIPANTS: The agreement between self reported high blood pressure status and data from medical records was measured in a representative sample of men and women (n = 248) aged 30-69 years. Medical records were studied for a diagnosis of high blood pressure, an anti-hypertensive pharmacological treatment or subject's inclusion in a hypertension control programme run in the medical centre only for hypertensive people (definite high blood pressure cases). As well, in the absence of such a diagnosis, medical annotations of systolic or diastolic high blood pressure > or = 140/90 mm Hg (possible high blood pressure cases) were considered. Sensitivity, specificity, positive and negative predictive values and kappa scores were calculated for all, definite and possible high blood pressure cases. Variables associated with the probability of having a true positive or negative self report of high blood pressure were also tested. MAIN RESULTS: As expected, sensitivity was higher among definite cases (72.7%) than among possible cases (31.6%). Accordingly, the agreement between self report and medical record was higher for definite cases (kappa = 0.65) than for possible (kappa = 0.29 cases leading to a moderate overall agreement for all cases (kappa = 0.58; 95% CI: 0.47, 0.69). Having some level of education (OR: 0.31; 95% CI: 0.09, 1.05) was negatively associated to a true self report of high blood pressure while being female was positively associated (OR: 4.01; 95% CI 1.04, 16.8). No variable showed any association with having a true self report of being normotensive. CONCLUSIONS: High blood pressure self report shows a moderate agreement with medical information in this cohort allowing it to be used, with caution, as a surrogate variable of actual blood pressure status. However, because of its moderate sensitivity, it is not possible to rule out some underestimation when using self reported high blood pressure information for high blood pressure frequency measurements such as prevalence or incidence rates. This underestimation will be higher among men and educated people.     

Bladder cancer screening program for a petrochemical cohort with potential exposure to beta-napthylamine

Approximately 1800 workers in pipe manufacturing plants in the United States may have been exposed to beta-napthlyamnine between 1970 and 1996. Once the chemical was detected, the contaminated additive in the resin was identified and discontinued. A bladder cancer-screening program was initiated in 1999. An annual two-stage screening program was developed to test for microscopic hematuria (stage one) and cytology (stage two), with a urology referral of positive or suspicious cytology. This paper presents the program methodology, cohort enumeration, recruitment, and enrollment strategies, and screening protocol. Enrollment data from the first 3 years are presented. Annual screening of a cohort of current and former employees is feasible. Original personnel records are often incomplete, making cohort identification important. Personal contact and follow-up are key elements of successful recruitment and retention.     

Navigating the Cancer Information Environment: The Reciprocal Relationship Between Patient–Clinician Information Engagement and Information Seeking from Nonmedical Sources

Prior theory has argued and empirical studies have shown that cancer patients rely on information from their health care providers as well as lay sources to understand and make decisions about their disease. However, research on the dynamic and interdependent nature of cancer patients’ engagement with different information sources is lacking. This study tested the hypotheses that patient–clinician information engagement and information seeking from nonmedical sources influence one another longitudinally among a representative cohort of 1,293 cancer survivors in Pennsylvania. The study hypotheses were supported in a series of lagged multiple regression analyses. Baseline seeking information from nonmedical sources positively predicted subsequent patient–clinician information engagement at 1-year follow-up. The reverse relationship was also statistically significant; baseline patient–clinician information engagement positively predicted information seeking from nonmedical sources at follow-up. These findings suggest that cancer survivors move between nonmedical and clinician sources in a dynamic way to learn about their disease.     

Effectiveness of source documents for identifying fatal occupational injuries: a synthesis of studies.

BACKGROUND: The complete and accurate identification of fatal occupational injuries among the US work force is an important first step in developing work injury prevention efforts. Numerous sources of information, such as death certificates, Workers' Compensation files, Occupational Safety and Health Administration (OSHA) files, medical examiner records, state health and labor department reports, and various combinations of these, have been used to identify cases of work-related fatal injuries. Recent studies have questioned the effectiveness of these sources for identifying such cases. METHODS: At least 10 studies have used multiple sources to define the universe of fatal work injuries within a state and to determine the capture rates, or proportion of the universe identified, by each source. Results of these studies, which are not all available in published literature, are summarized here in a format that allows researchers to readily compare the ascertainment capabilities of the sources. RESULTS: The overall average capture rates of sources were as follows: death certificates, 81%; medical examiner records, 61%; Workers' Compensation reports, 57%; and OSHA reports 32%. Variations by state and value added through the use of multiple sources are presented and discussed. CONCLUSIONS: This meta-analysis of 10 state-based studies summarizes the effectiveness of various source documents for capturing cases of fatal occupational injuries to help researchers make informed decisions when designing occupational injury surveillance systems.