Use of administrative databases in occupational and environmental epidemiologic research

A hospital-based case-control study of non-Hodgkin lymphoid neoplasms in Shanghai: analysis of personal characteristics, lifestyle, and environmental risk factors by subtypes of the WHO classification

OBJECTIVES

To investigate potential risk factors (personal characteristics, lifestyle, and environmental factors) of non-Hodgkin lymphoid neoplasms (NHLN), including lymphomas and lymphocytic leukemia, according to the World Health Organization classification.

MATERIALS AND METHODS

The investigation was a hospital-based case-control study consisting of 649 confirmed NHLN cases and 1298 individually gender-age-matched patient controls at 25 hospitals in Shanghai. A 17-page questionnaire was used to obtain information on demographics, medical history, family history, lifestyle risk factors, employment history, residential history, and occupational and non-occupational exposures. Risk estimates were calculated using conditional logistic regression models.

RESULTS

Potential risk factors of NHLN (all subtypes combined) or individual subtypes included low-level education, home or workplace renovation, living on a farm, planting crops, and raising livestock or animals. Some risk factors applied to all or most subtypes (such as lowlevel education, living on a farm, and raising livestock or animals), whereas others did not (such as the use of traditional Chinese medicines, which was associated with a reduced risk). Blood transfusions, hair dyes, or living near high-voltage power lines were not associated with an increased risk.

CONCLUSIONS

The study identified a number of risk factors for NHLN overall and specific subtypes. Some risk factors were subtype-specific. The difference in risk by subtype underscores the etiologic commonality and heterogeneity of NHLN subtypes.

Health care use associated with work-related musculoskeletal disorders among hospital workers

INTRODUCTION

The purpose of this study was to investigate if work-related musculoskeletal disorders (WMSDs) are associated with increased health care use, over and above workers' compensation health care benefits, in the period prior to and following a workers' compensation claim indicating gradual progression and declining function associated with musculoskeletal morbidity.

METHODS

This study employed secondary analysis of employment data, workers' compensation claim data and provincial (universal) medical services data for a cohort of health care workers; and investigated rates of medical care contacts among injured workers with a WMSD claim (n=549) compared to a matched group of non-claim workers. Predictors of health care contacts were estimated using general linear regression.

RESULTS

WMSD injured workers had significantly higher rates of health care contacts associated with a claim compared to non-injured workers, over and above workers compensation health care benefits. In the final multi-variable model, a WMSD claim among injured workers was associated with an estimated 69% (95% CI, 1.50, 1.91) increase in health care use for the 12-month period immediately after the injury date compared to non injured workers.

CONCLUSION

The pattern of visits for WMSDs suggests that workers visit general practitioners as part of an ongoing pattern of symptoms, resulting in frequent utilization of health services prior to work disability that is also reflected in health care contacts after return-to-work.

Exposure to benzene and non-Hodgkin lymphoma, an epidemiologic overview and an ongoing case-control study in Shanghai

The interest in the relationship between benzene exposure and non-Hodgkin lymphoma (NHL) appears to have been generated from a 1979 publication, which reported an increased risk of NHL among persons potentially exposed to benzene and/or coal tar fractions. More recently (1997), an increased risk of NHL was reported among 74,828 workers exposed to benzene and other chemicals in a variety of industries in China. On the contrary, no increased risk of NHL was reported in a cohort of 1,165 workers at two rubber hydrochloride plants in Ohio (US), who were exposed to extremely high levels of benzene and were found to have an increased risk of acute myeloid leukemia. In another large cohort of some 7,676 US workers exposed to benzene, no increased risk of NHL was reported. Similarly, no increased risk of NHL was reported in a combined cohort of 308,199 petroleum workers in the US, the UK, Canada, Australia, Italy and Finland, who were exposed to benzene or benzene-containing petroleum products. The lack of an association between benzene exposure and NHL in cohort studies is supported by case-control studies from the US, Canada, Italy and the UK. To further investigate the relationship between benzene exposure and NHL, we are conducting a hospital-based case-control study in Shanghai, China. Cases are newly diagnosed NHL patients at 29 hospitals in Shanghai. For each case, two matched controls are selected among patients without any lymphatic or hematopoietic diseases at the same hospital. Demographic, employment, medical and lifestyle information is obtained through questionnaires (primary and secondary). Sources for benzene exposure information include a database of 50,000+ benzene measurements maintained by the Shanghai Municipal Institute of Public Health Supervision (IPHS), Shanghai District IPHS, walk-through surveys at factories, additional measurements at factories and reports in Chinese medical journals. Patient enrollment started in 2003 and it is estimated that the study will have 400-450 NHL cases by December 2006. Some of the occupations or industries reported among enrolled study subjects (cases and controls) with potential exposure to benzene include shoe workers, painters, mechanics or machinists, and printers. Some of the unique features of the study are discussed.

Winter respiratory viruses and health care use: a population-based study in the northwest United States

To quantify health care use among adults during influenza and respiratory syncytial virus (RSV) seasons, we identified a cohort of veterans aged >or=18 years who used Department of Veterans Affairs (VA) facilities in Oregon and Washington states as their source of health care. During 1998-2000, veterans accrued 237,159 person-years of follow-up. Using VA data sources, we measured acute cardiopulmonary hospitalizations and primary care and urgent care visits. Differences between rates of study events when influenza and/or RSV were circulating and event rates when neither virus was circulating were used to calculate winter virus-attributable morbidity. Inpatient and outpatient event rates were consistently higher during winter virus season, compared with non-winter virus season. Annual rates of cardiopulmonary hospitalizations attributable to influenza or RSV infection ranged from 0.8 (95% confidence interval [CI], 0.1-1.5) per 1000 low-risk individuals aged 18-49 years, to 10.6 (95% CI, 7.5-13.6) per 1000 high-risk individuals aged >or=65 years. Each year, circulation of influenza and RSV coincide with predictable increases in medical care use.

Is There a Causal Relationship Between Exposure to Diesel Exhaust and Multiple Myeloma?

This article presents a comprehensive critical review of the epidemiology of multiple myeloma in relation to occupational diesel exhaust exposure. The review includes cohort and proportional mortality studies of workers exposed to diesel exhaust, and population-based case-control studies of multiple myeloma. None of the cohort or proportional mortality studies reported a significant increase of multiple myeloma in relation to diesel exhaust, with the exception of a study of Danish truck drivers. Several limitations in this Danish study (such as inadequate cohort identification, small number of multiple myeloma deaths and inappropriate analytical method) made the result unreliable. Furthermore, the data in this study of Danish truck drivers were part of and, hence, superseded by a large study in Denmark, which did not find any increased risk of multiple myeloma. Similarly, none of the case-control studies reported a significant increase of multiple myeloma in relation to diesel exhaust, with the exception of the smallest case-control study based on multiple myeloma patients in central and southeast Sweden. The result of this small Swedish study was not reliable because of incomplete case ascertainment, inappropriate controls and confounding. Furthermore, the data in this small Swedish study were part of and, hence, superseded by a large national study of workers exposed to diesel exhaust in Sweden, which did not find any increased risk of multiple myeloma. Other than the study of Danish truck drivers and the small case-control study of multiple myeloma patients in central and southeast Sweden, all other epidemiological investigations consistently reported no increase of multiple myeloma in relation to occupational diesel exhaust exposure. Furthermore, none of the studies reported a positive exposure-response relationship between diesel exhaust and multiple myeloma. Several studies that analysed data by jobs or occupations according to level of exposure and by duration of exposure did not find any upward trend. In addition to the review, a formal causation analysis based on an application of the Hill criteria confirms that there is no causal relationship between diesel exhaust and multiple myeloma.