Acute occupational respiratory diseases in hospital discharge data

Hospital discharge data: can it serve as the sole source of case ascertainment for population-based birth defects surveillance programs?

INTRODUCTION

Because of the relatively high expense of collecting primary data and limited resources, electronically available, population-based hospital discharge data have been increasingly used for disease surveillance by public health researchers. The objective of this study was to compare the New York State Congenital Malformations Registry (CMR) data, which relies on hospital reports, with the hospital discharge files to identify cases in the CMR that were missed in the hospital discharge data files. The ultimate goal was to evaluate whether hospital discharge data can serve as the sole source of case ascertainment for a population-based birth defects surveillance program.

METHODS

CMR cases that were born to the New York State residents for the years 2000 to 2005 were selected and matched to the hospital discharge files from the New York Statewide Planning and Research Cooperative System (SPARCS) for the same birth year period. Since the SPARCS database does not contain patient's name, extensive database matching and manual review by staff members were performed using identifying variables such as the hospital's permanent facility identifier, child's date of birth and medical record number, and mother's medical record number and residential address.

RESULTS

Out of 66 757 CMR cases selected for the study period, 62 118 cases (93.1%) were matched to SPARCS hospital discharge records with International Classification of Diseases, Ninth Revision (ICD-9) codes that were reportable to the CMR, 3 444 cases (5.2%) were matched to SPARCS records with ICD-9 codes that were not reportable to the CMR, and 1 195 cases (1.8%) were not matched. The percentage of cases with multiple congenital malformations was significantly higher (21.3%) for the matched cases that had reportable ICD-9 codes in SPARCS, compared with that for matched CMR cases that had no reportable ICD-9 codes in SPARCS (10.2%).

CONCLUSION

The study found that 93% of CMR infants selected for the study were matched to hospital discharge records with at least one ICD-9 code that was reportable to the CMR; 87 percent had reportable ICD codes in SPARCS that were exactly matched to those in the CMR, that is, all the birth defect codes in SPARCS were matched to those in the CMR. Thus, about 7 percent of CMR children with birth defects would have been missed if only hospital discharge files were used to ascertain the birth defect cases, indicating that there are limitations to using hospital discharge files as the sole source of case ascertainment for population-based birth defects surveillance programs.

Use of hospital discharge data for surveillance of chemical-related respiratory disease

Hospital discharge data can be useful in the identification of the more severe cases of both work- and nonwork-related chemical-related respiratory disease. The medical records of 329 patients hospitalized in Michigan in 1989 and 1990 for respiratory conditions resulting from chemical fumes and vapors (International Classification of Diseases diagnostic code 506) were reviewed to determine the location and etiology of the exposures. One-third of the discharges were work related. The most common exposures at work were to chlorine and sulfur dioxide and to industrial cleaning agents. Exposure to smoke from house fires and exposure to household cleaners were the most frequent causes of the nonwork-related discharges. Follow-up inspections at the work facilities where the hospitalized patients with work-related disease had become ill revealed that 61 of 261 (23.4%) fellow workers interviewed had new adult-onset asthma or were bothered at work by daily or weekly symptoms of shortness of breath, wheezing, or chest tightness. Nine of the 23 facilities inspected were cited for violating Occupational Safety and Health Administration standards.

Occupational factors in work-related inhalations: inferences for prevention strategy

As part of a larger investigation of inhalational toxic exposures, we studied occupationally related cases in order to examine possible preventive strategies. We analyzed data from 224 structured interviews. Of the interviewed subjects, 48 (21%) reported closed space exposures and 44 (20%) concomitant skin exposure at the time of inhalation. Chlorine gas and bleach mixtures were the most common single reported exposure type, occurring in 54 (24%) of cases. The most common occupational groups represented were crafts workers, operatives, and laborers (n = 84, 38%), and service workers (n = 64, 29%). Adjusting for occupational group in a multiple logistic regression analysis that also included length of hire and access to personal respiratory protective equipment, report of prior specific chemical safety training was significantly protective against closed space inhalation (odds ratio (OR) = 0.2; 95% confidence interval (CI) 0.1-0.4) and concomitant skin exposure (OR = 0.3, 95% CI = 0.1-0.7). These data suggest that chemical safety training may be an effective preventive strategy for potentially high-risk inhalational exposure scenarios.

An evaluation of New Jersey's hospital discharge database for surveillance of severe occupational injuries

Computerized population-based hospital discharge data in New Jersey offer new opportunities for surveillance of serious work-related injuries. This database was evaluated for its potential in identifying selected injuries that occurred at work during 1985 and 1986. Hospital discharge data were compared with data collected by telephone interview of discharged patients. A total of 1,575 unique hospital discharge records for the selected injuries included finger amputation (1,041), thumb amputation (209), crush injury of the lower limb (208), toxic effects of heavy metals (69), and eye burns (48). Of 809 study subjects sent letters, 445 (55%) could be contacted and 289 (36%) were interviewed for the study. Sixty-one percent (175) said their injury was work related. A comparison was made between self-reported injury at work, and the presence of workers' compensation payer codes on the discharge database. The agreement beyond chance (Kappa) was 0.78 (95% CI = 0.67, 0.89). The sensitivity of this indicator of work relatedness was 83%; specificity was 98%. These data suggest that workers' compensation payment on the hospital discharge database may be a good to excellent proxy indicator of the work relatedness of these injuries. However, this proxy indicator will underestimate the number of work-related injuries by about 20%. Only 11% of hospital discharge records had external cause of injury codes (E-codes), which reduces the utility of the database for understanding the causal mechanisms of work-related injuries.