Longitudinal changes in the prevalence of adult asthma: An epidemiological survey among Japanese salaried employees and their dependents using healthcare insurance claim from 1999 to 2019

BACKGROUND

Information on changes in asthma prevalence and the treatment status for asthma is used as basic information for taking medical and administrative measures against asthma. However, this information among adults is relatively limited.

METHODS

To elucidate changes in the prevalence of asthma and treatment status over time among Japanese adults, health insurance claim data from some health insurance societies covering salaried employees and their dependents were studied longitudinally. Claim data from FY1999 to 2007 were obtained from two health insurance societies, and data from FY 2011 to 2019 were obtained from three different health insurance societies, and changes in standardized asthma prevalence among subjects aged 20-59 years, proportion of asthma patients prescribed ICS, leukotriene receptor antagonist (LTRA), and LABA, and the mean number of acute asthma exacerbations per year were analyzed.

RESULTS

The prevalence of asthma increased from 1.6% in 1999 to 3.0% in 2007 and 2.9% in 2011 to 4.6% in 2019. Increased trends in asthma prevalence from 2011 to 2019 were more noticeable in subjects in their 50s than those in their 20s for both sexes. The number of emergency visits related to asthma was 1.5 per year in 1999, which decreased to 0.8 per year in 2019. The proportion of people prescribed all anti-asthma medications (ICS, LTRA, and LABA) increased over time.

CONCLUSIONS

The prevalence of adult asthma among Japanese salaried employees and their dependents has increased over the last 20 years, suggesting more attention should be paid to the prevention of this disease in adults.

Obesity, but not metabolic syndrome, as a risk factor for late-onset asthma in Japanese women

BACKGROUND

Several cross-sectional studies have suggested an association between obesity and asthma. However, few studies have investigated this relationship longitudinally, especially in middle-aged subjects. Although metabolic syndrome is a well-known risk factor for many non-communicable diseases, its contribution to asthma remains controversial.

METHODS

From 2008, specific health checkups for metabolic syndrome have been conducted throughout Japan. To seek relationships of obesity and metabolic syndrome with late-onset asthma in Japan, we analyzed data collected from health insurance claims and specific health checkups for metabolic syndrome at three large health insurance societies. Among subjects aged 40-64 years (n = 9888), multivariate logistic regression analyses were performed to investigate the relationships of obesity and metabolic syndrome in fiscal year 2012 (from April 2012 to March 2013) with the incidence of late-onset asthma in the following two years (from April 2013 to March 2015).

RESULTS

In women, BMI 25-29.9 kg/m² or ≥30 kg/m², waist circumference ≥90 cm, and waist-to-height ratio ≥0.5 were shown to be significant risk factors for asthma, with adjusted odds ratios (95% CI) of 1.92 (1.35-2.75), 2.24 (1.23-4.09), 1.89 (1.30-2.75), and 1.53 (1.15-2.03), respectively. Significance was retained even after adjustment for metabolic syndrome, and there were no significant relationships between metabolic syndrome itself and the incidence of asthma in men or women.

CONCLUSIONS

Only the obesity measures, not metabolic syndrome, were shown to be significant risk factors for the incidence of late-onset asthma but only in middle-aged Japanese women, and not in men.