All 202 adult patients with a primary hospital discharge diagnosis of asthma in 1990 were selected from three Michigan hospitals for a possible interview. Ninety-four of these patients were interviewed. Of the 108 nonresponders, 2 had died, 19 refused, and 87 could not be located after a mailing and an attempted phone call. There was no significant difference between the gender of the nonresponder and responder groups (x2 = 0.013, p = 0.971) (Table 2). However, the responders were on the average 7 years older (p = 0.0001). A larger percentage of patients who responded were covered by private insurance (68.8 percent vs 34.3 percent) and a lower percentage were covered by Medicaid (20.8 percent vs 51.4 percent). A larger percentage of patients responded from hospitals A (50.8 percent) and С (69.2 percent) than hospital В (35.2 percent) (x2 = 7.23, p = 0.023).
Three patients (3.2 percent) met the criteria for having probable occupational asthma, and 17 patients (18.1 percent) met the criteria for having possible occupational asthma. There was one patient with probable occupational asthma from each hospital. Short summaries of the patients who were classified as having probable occupational asthma are included below.
A woman in her late 50s who began working as a transcriptionist in the pathology department of a large hospital and presently worked as a supervisor in the same area developed symptoms of shortness of breath, chest tightness, and wheezing after working at the job for 11 years. The patients symptoms improved when she was not at work. She had a 25-year history of smoking one half a pack of cigarettes per day. She had a family history of asthma and a personal history of allergies that began at the age of 7 years. She had to walk through the laboratory where formaldehyde was used on a daily basis. In addition, one of her job duties required that she enter the laboratory to discuss specific procedures with the laboratory personnel. Formaldehyde, which is typically used in a pathology laboratory, has been reported to cause occupational asthma.
A man in his late 20s developed wheezing and a dry throat 2 years after beginning to work as an automation technician at company manufacturing automobile parts. His symptoms were associated with work and improved on weekends and vacations. He had smoked one half a pack of cigarettes a day for 14 years. He also had a history of childhood asthma but had been asymptomatic for 2 years prior to the occurrence of his symptoms at the new occupation. He had a daughter with asthma and a history of allergies that began in early childhood. He also reported having a history of chronic bronchitis at the age of 9 years that had not persisted.
He was exposed on a daily basis to oil mist. Case reports and one epidemiologic study have associated exposure to aerosolized coolants with bronchoconstrietion.
A man in his early 50s who had been working as a firefighter for 28 years developed symptoms of wheezing and shortness of breath after fighting a fire in a kitchen of a residence hall at a large university. He continued to work for 6 more years as a firefighter, at which time his symptoms worsened after a fire at a dentists office. He had not worked at any job since that time. He had been a smoker for 34 years and smoked about a pack per day. He did not have a personal or family history of asthma. The patient reported he was told he also had chronic bronchitis. He had a history of allergies. Asthma has been reported to develop after exposure to smoke. This was the one patient whose hospitalization was covered by workers compensation.
Table 2—Characteristics of Responders and Nonresponders
|Average age,* yr||44||37||0.0001|
|Average length of stay,t d||4.00||4.40||NS|
|Insurance,$ No. (%)||0.0114|
|Private||33 (68.8)||12 (34.3)|
|Medicare||5 (10.4)||5 (14.3)|
|Medicaid||10 (20.8)||18 (51.4)|
|Worker compensation||1 (2.1)||0 (0)|
|ICD codes,§ No. (%)||NS|
|493.0||12 (17.4)||14 (23.7)|
|493.1||25 (36.2)||17 (28.8)|
|493.9||24 (34.8)||20 (33.9)|
|Have more than one of the above ICD codes||8 (11.6)||8 (13.6)|