Original article
Sex difference in hospitalization due to asthma in relation to age

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Abstract

To describe the sex and age differences in asthma hospitalization among the Canadian population, we conducted an analysis based on a total of 9,486,173 hospital records in Canada for a 3-year period (1994/1995, 1995/1996, and 1996/1997), including 204,304 asthma patients and 288,977 asthma-related records. Asthma as one of the first five diagnoses, accounted for 3.0% of total hospitalizations, which was almost constant across the 3-year study period. The 3-year cumulative incidence of asthma hospitalization was substantially higher for young boys than girls, and it was reversed for adults. The incidence ratio for females vs. males for asthma hospitalization reached 2.8 for individuals 25 to 34 years of age, decreased gradually with increasing age, and then approached unity for those aged 80 years or more. The data suggest that sex is an important determinant for asthma, and the sex effect varies considerably over a life span.

Introduction

Asthma is a multifactorial disease, and its genetic and environmental risk factors have not been fully understood. Sex and age are important determinants of asthma occurrence and hospitalization, and the effect of sex on asthma varies with age. Several epidemiologic studies have documented sex differences in asthma prevalence, incidence, and hospitalization, and these differences change considerably over the life span 1, 2, 3, 4, 5, 6, 7. Results from previous studies are consistent for young children that boys have a higher risk of asthma compared with girls, and such a difference is more pronounced in early childhood 1, 2, 3, 4, 5, 6. The influence of sex on asthma has a different pattern among adolescents and adults. Somehow the sex difference in asthma risk disappears during puberty, and then adolescent girls overtake adolescent boys and have more asthma [7]. Greater prevalence [5], incidence [6], and hospitalization [2] of asthma have been found in women than in men. However, it is not clear if the sex difference stays similar in adults across ages.

The aim of this analysis was to examine the interrelationship among sex, age, and hospitalization due to asthma using a national hospitalization database, which contained almost all hospitalizations of the Canadian residents over a 3-year period, with an individual linkage using a standardized health identification number (HIN). Because of the large size of study population, we were able to observe detail changes in the incidence of asthma hospitalization over the life span in both sexes. We discussed a number of hypotheses for such sex- and age-related changes in asthma hospitalization.

Section snippets

Methods

We used the hospital discharge (separation) data collected by the Canadian Institute for Health Information. Each record contains information abstracted from a patient's hospital chart, and pertains to one hospital stay. These records were subjected to linkage procedures to create person-oriented information on patients diagnosed with asthma. Hospital records for each province for the fiscal years 1994/1995 to 1996/1997 were linked using patient identification numbers. The information is

Results

There were approximately 9.5 million hospitalizations with a valid HIN from 1994/1995 to 1996/1997 in Canada excluding Yukon Territory. Table 1 shows that 3.0% of these hospitalizations had asthma listed as one of the first five underlying diagnoses, and 1.5% had asthma listed as the first underlying diagnosis. The proportion of asthma hospitalization, either broadly or narrow defined, was constant across the 3-year study period, while the number of both total hospitalizations and

Discussion

Asthma is an important disease that imposes a heavy burden on the health care system in all countries studied [9]. In an analysis based on the 1987 National Medical Expenditure Survey in the Unite States, Smith et al. [10] estimated direct expenditures of $5.1 billion and indirect expenditures of 673 million in 1994 U.S. dollars for asthma in that country, with a significant portion of the expenditures being accounted for by hospitalizations. In Canada, the total costs of asthma in 1990 were

Acknowledgements

Yue Chen is a Canadian Institutes of Health Research Investigator Award recipient. The authors thank Gary Catlin and Cyril Nair for their helpful comments, and Peter Walsh, John Menic, and Trong Huynh for their assistance in data access and computing.

References (37)

  • D.H Smith et al.

    A national estimate of the economic costs of asthma

    Am J Respir Crit Care Med

    (1997)
  • M.D Krahn et al.

    Direct and indirect costs of asthma in Canada, 1990

    Can Med Assoc J

    (1996)
  • W.J Ungar et al.

    The patient level cost of asthma in adults in south central Ontario

    Can Respir J

    (1998)
  • T Tuuponen et al.

    Trends in hospitalization among asthmatic children in Finland from 1972 to 1986

    Eur J Pediatr

    (1993)
  • O Eliasson

    The male–female ratio of hospital admission for asthma

    Am Rev Respir Dis

    (1980)
  • A Senthilselvan

    Effect of readmissions on increasing hospital admissions for asthma in children

    Thorax

    (1995)
  • M Green et al.

    Variability of maximum expiratory flow-volume curves

    J Appl Physiol

    (1974)
  • J Mead

    Dysanapsis in normal lungs assessed by the relationship between maximal flow, static recoil, and vital capacity

    Am Rev Respir Dis

    (1980)
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