Influence of gender on rates of hospitalization, hospital course, and hypercapnea in high-risk patients admitted for asthma : a 10-year retrospective study at Yale-New Haven Hospital

Abstract

Study objectives: To compare the relative numbers and hospital course of men vs women admitted at least twice with asthma or status asthmaticus to Yale-New Haven Hospital (YNHH) during the period from 1985 to 1994.

Design: A retrospective chart review.

Setting: YNHH.

Patients: High-risk men and women (age range, 18 to 50 years) admitted at least twice during the study period with the discharge diagnosis of asthma or status asthmaticus.

Results: Of 561 adult asthma patients admitted during the study period, 188 were admitted at least twice and accounted for 68% of the total asthma admissions. One hundred three of the 188 patients were randomly selected, and all of their asthma admissions were retrospectively reviewed. The 103 patients accounted for 382 admissions. Seventy-two percent of these patients and 68.6% of the admissions were women. The proportions of each gender requiring admission to the medical ICU (15.65% women vs 11.67% men) or intubation (8.00% women vs 5.80% men) were not significantly different. Women did exhibit a definite trend toward longer admissions (4.92 days vs 4.04 days; p < 0.554). A significantly higher proportion of female patient admissions underwent initial arterial blood gas analysis than men (56.9% vs 44.2%; p < 0.05). Factorial analysis demonstrated a highly significant main effect of gender on PCO(2) levels (p < 0.0001). Men, overall, had higher PCO(2) levels than women (48.73 mm Hg vs 41.04 mm Hg; p < 0.036). Male patients admitted to the medical ICU or requiring intubation had significantly higher PCO(2) levels than their respective female counterparts (p < 0.05).

Conclusions: At YNHH, 68% of all admissions for asthma in this age group are attributable to high-risk patients. High-risk female patients are admitted twice as often as high-risk male patients and tend to have longer admissions. Once admitted, however, the proportion of men and women requiring the medical MICU or intubation were similar. High-risk male patients on presentation are consistently more hypercapneic than high-risk female patients. Therefore, the mechanisms contributing to the gender differences in asthma admissions may include differences in the ventilatory response to hypercapnea or in the tolerance to airway obstruction.