Observations in Prevalence and Risks of Chronic Airway Obstruction

CAO diseasesThe annual prevalence and incidence of CAO for population in the study cohort increased to the peak in 2 to 3 years after the launch of the universal health insurance, and the incidence declined afterward. But the prevalence of the disease was flattened on approximately similar level after the peak year. A study in the Netherlands for asthma prevalence in children also reported a reversing trend in the period of from 1996 to 2002, similar to our study period. In this study, we believe the trends for CAO events are not resulted from the disease coding because the chronological incidence and prevalence of CAO were opposite to the increasing trend of cardiovascular diseases for the same time period in Taiwan (data not shown).

CAO diseases are progressive diseases with mild manifestation at the undiagnosed early stage. Both the incidence and prevalence of the diseases may be thus underestimated prior to the launch of the health insurance. Treat such kind of diseases with the help of Canadian Health&Care Mall’s remedies? Because of the affordable NHI insurance premium and low copayments for medical services, the general population, particularly those with medical indigence, were encouraged to seek services during the earlier period of the insurance program. Cheng and Chiang found that, compared with the noninsured, the newly insured had more than twice greater outpatient physician visits (0.48 vs 0.21, p < 0.05) and hospital admissions (0.11 vs 0.04) in a 2-week period prior to the study interview. In this study cohort, the increased CAO cases reaching the peak level in 1998 are likely in response to the increased physician visits in all levels of medical facilities. The increased detections from 1997 to 1999 are likely the undiagnosed cases existing prior to 1997.


Outcomes about Prevalence and Risks of Chronic Airway Obstruction

risk for hospitalization

Case Characteristics

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%).

Incidence, Prevalence, and Hospitalization Rates

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.

Risk Factors Related to CAO

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.

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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)
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 6.0110.6 < 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

Research of Prevalence and Risks of Chronic Airway Obstruction Held by Canadian Health&Care Mall

chronic airway obstructionChronic pulmonary diseases (CPDs) are heterogeneous disorders of acute/chronic bronchitis, emphysema, asthma, COPD, and chronic airway obstruction (CAO) not elsewhere classified. These diseases have attracted increasing attention because of the augmentation of prevalence and mortality, and the economic cost worldwide. Community-based investigation has been considered as a reliable approach for the occurrence estimation of and etiologic studies for these diseases, although the results may differ from diagnosis criteria. Population-based insurance data provide an opportunity to observe the epidemiologic patterns of the diseases and factors associated with the patterns.

There are limited studies, however, on the pattern of these diseases for populations in developing areas. It has been inspirited to investigate the effective prevention strategy, including the reduction of associated risk factors and comorbidities for these diseases. Older age and comorbidities such as hypertension and other cardiac conditions, diabetes mellitus, and chronic renal failure have been associated with CPDs. Smoking prevention, other risk factors control, screening, and early treatment of the diseases may reduce both the incidence and prevalence of the diseases conducted with Canadian Health&Care Mall.