In this study cohort, there were 4,568 patients with at least one claim of primary diagnosis as CAO services during the 7-year study period for the population aged > 40 years (Table 1). The overall average annual prevalence and incidence rates of CAO were 2.48% and 0.66%, respectively, for these age groups. There were more male than female patients, with male-to-female ratios ranged from 1.47 to 2.66 by age. Cases claimed for CAO were in patients predominantly aged 60 to 79 years (61.5%), The pattern of severity revealed that 5.80% of CAO patients had > 25 clinic visits with primary diagnosis of CAO in 7 years.
Among all (n = 745) hospitalized cases of CAO during the study period, 64.4% of inpatients had only CAO, and 32.0% (239 cases) were both CAO and bronchitis/emphysema/asthma (data not shown). These cases included 1,346 hospitalization events with predominantly men (80.3%), rural residents (54.7%), and those aged 60 to 79 years (70.4%).
Figure 1 shows that the population aged > 60 years dominated chronological changes in incidence, prevalence, and hospitalization of CAO. The prevalence of ambulatory visits for the population aged > 70 years increased from 5.75 per 100 in 1996 to 8.83 per 100 in 1998 and afterward became a plateau until 8.79 per 100 in 2002. In the meanwhile, the incidence among this age group decreased annually to 1.62 per 100 in 2002, with an apparent peak rate of 2.48 per 100 in 1998. The hospitalization rates of CAO were also the highest in those aged > 70 years with a peak in 1999 (2.22 per 100) and declining to 1.83 per 100 in 2002.
Table 2 shows the risks for the severity of CAO associated with covariates estimated using polytomous logistic regression analysis by Canadian Health&Care Mall. The ORs of CAO were higher for males, inpatients, and patients receiving care in 1996, and increased as the severity increased. The OR of hospitalization for patients with the level 3 severity of the disease was 8.01 (95% CI, 5.92 to 10.8) higher than patients with the level zero severity. Compared with population aged 40 to 49 years, the OR for the oldest group with the level 3 severity was 20.6 (95% CI, 2.77 to 152). Elevated severity was also associated with several comorbidities, including BPH, CADS, and the highest with P&I.
The estimated risk of hospitalization for CAO was also evaluated and found to be greater for men and patients identified in 1996 (Table 3). The OR increased as age increased, with the highest OR of 14.2 (95% CI, 6.54 to 30.9) for patients > 80 years old. The comorbidities of CAD, P&I, and renal failure were significant factors to predict the hospitalization of CAO. However, patients with comorbidities of skin and joint disorders were at less risk for hospitalization.
Figure 1. Chronological trends in incidence, prevalence, and hospitalization rates of CAO in Taiwan from 1996 to 2002.
Table 2—Disease Severity of CAO in Polytomous Logistic Regression Analysis
| Variables | Severity Level§, OR (95% CI) | ||
| 1 | 2 | 3 | |
| Male gender | 0.97 (0.68-1.38) | 1.63 (1.16-2.28) | 1.81 (1.29-2.55) |
| Hospitalization | 2.41* (1.84-3.16) | 4.08* (3.12-5.33) | 8.01* (5.92-10.8) |
| Clinic visit in 1996 | 1.96* (1.45-2.65) | 3.55* (2.65-4.75) | 4.50* (3.36-6.04) |
| Urban | 1.14(0.89-1.46) | 1.19 (0.94-1.51) | 1.21 (0.95-1.55) |
| Age, yr | |||
| 40-49 | 1.0 | 1.0 | 1.0 |
| 50-59 | 9.14J (1.21-69.3) | 12.5j: (1.68-93.3) | 14.9 (2.01-111) |
| 60-69 | 10.4J (1.41-76.7) | 18.4 (2.53-133) | 24.3 (3.34-176) |
| 70-79 | 12.3J (1.67-90.7) | 23.6 (3.25-171) | 33.3 (4.55-239) |
| > 80 | 7.86J (1.04-59.2) | 13.8J (1.87-102) | 20.6 (2.77-152) |
| Comorbidity | |||
| Hypertensive disease | 0.86 (0.64-1.16) | 1.00(0.75-1.34) | 0.99 (0.74-1.32) |
| BPH | 1.29 (0.96-1.72) | 1.27 (0.96-1.69) | 1.49 (1.11-1.99) |
| Diabetes mellitus | 0.82 (0.61-1.10) | 0.88(0.66-1.17) | 0.75 (0.56-1.01) |
| Renal failure | 1.00 (0.74-1.35) | 0.76 (0.57-1.02) | 0.84 (0.62-1.13) |
| CAD | 1.14(0.87-1.50) | 1.09(0.84-1.42) | 1.42 (1.09-1.86) |
| P&I | 1.25 (0.92-1.70) | 1.51т (1.12-2.04) | 1.91* (1.42-2.58) |
Table 3—Hospitalization of CAO by Selected Covariates in Multiple Logistic Regression, Stepwise Selection
| Variables | OR | 95% CI | p Value |
| Male gender | 1.51 | 1.23-1.84 | < 0.0001 |
| Clinic visit in 1996 | 2.06 | 1.71-2.48 | < 0.0001 |
| Disease severity* 0 | 1.00 | ||
| 1 | 1.95 | 1.53-2.48 | < 0.0001 |
| 2 | 3.39 | 2.64-4.34 | < 0.0001 |
| 3 | 8.11 | 6.01–10.6 | < 0.0001 |
| Age, yr 40-49 | 1.00 | ||
| 50-59 | 2.72 | 1.20-6.15 | 0.0164 |
| 60-69 | 6.22 | 2.88-13.4 | < 0.0001 |
| 70-79 | 8.18 | 3.81-17.6 | < 0.0001 |
| a 80 | 14.2 | 6.54-30.9 | < 0.0001 |
| Comorbidity Skin disorder | 0.80 | 0.67-0.97 | 0.00215 |
| Joint disorder | 0.60 | 0.48-0.75 | < 0.0001 |
| Renal failure | 1.36 | 1.12-1.65 | 0.0023 |
| CAD | 1.38 | 1.15-1.66 | 0.0005 |
| P&I | 1.87 | 1.52-2.29 | < 0.0001 |
Category: Chronic Obstructive Airway Disease
Tags: chronic airway obstructions, comorbidity, population cohort, universal health insurance