Concerns with the health check-up system for chronic obstructive pulmonary disease on two Japanese islands

Much lower prevalence and mortality of chronic obstructive pulmonary disease in Japan than in the US despite higher smoking rates: A meta analysis/systematic review

BACKGROUND

A recent systematic review showed Japan's mortality from chronic obstructive pulmonary disease (COPD) is the lowest among 204 countries, despite notably higher smoking rates in men in Japan than in the US. This study aims to compare (1) trends in smoking rates, (2) trends in COPD mortality, and (3) the spirometry-based COPD prevalence in the general adult population between Japan and the US.

METHODS

Age- and sex-specific smoking rates from the 1980s through 2010s and COPD mortality from 1999 through 2019 were obtained from national surveys and official statistics (International Classification of Diseases-10th codes J40-44), respectively. A systematic review and meta-analysis was performed to estimate COPD prevalence in Japan, while the National Health and Nutrition Examination Survey 2007-2012 was used for the US. A fixed ratio of 0.7 of forced expiratory volume in the first second of forced vital capacity was used to define COPD.

RESULTS

Over the past four decades, men in Japan consistently had 20-30% higher smoking rates than their US counterparts. From 1999-2019, age-adjusted COPD mortality in men in Japan was only a third of the US, whereas that in women was less than a tenth in 2019. Synthesizing data from 11 studies, involving 89,955 participants, Japan's COPD prevalence was more than 10% lower than in the US in almost all age groups for both sexes.

CONCLUSIONS

This study showed markedly lower rates of COPD in Japan than in the US. Investigating factors contributing to the paradoxical observations could lead to advancing COPD risk reduction strategies.

Effectiveness of diagnostic screening tests in mass screening for COPD using a cooperative regional system in a region with heavy air pollution: a cross-sectional study

OBJECTIVES

This study aimed to evaluate the effectiveness of a cooperative healthcare model for early detection and diagnosis of chronic obstructive pulmonary disease (COPD).

METHODS

This was a cross-sectional observational study. We performed diagnosis of COPD at 4 public health centres in Ōmuta, Japan from March 2015 to March 2016, by adding screening for COPD at the time of routine medical evaluations. All patients aged over 40 years were eligible to participate. Among 397 eligible patients, 293 agreed to participate in the study.

RESULTS

The estimated prevalence of COPD in Ōmuta was 10% among patients aged over 40 years and was 17% among smokers. Among those who were screened, over half of them had questionnaire scores over the cut-off of 17 points and decreased FEV1/FVC%, indicating COPD (p>0.05). 30 patients with suspected COPD were referred for further investigation at a local central hospital, but only 6 underwent further medical examinations.

CONCLUSIONS

The combination of a COPD questionnaire and medical examination is effective as a COPD screening tool. Future research should investigate behavioural interventions for smoking cessation that can be offered in a cooperative model, as well as for improving participation in COPD screening and for encouraging early presentation for treatment in those suspected of having COPD.

The physiological characteristics of community-dwelling elderly Japanese with airflow limitation: a cross-sectional study

BACKGROUND AND AIMS

The aim of this study was to investigate the physiological characteristics of community-dwelling elderly subjects, aged ≥65 years, with airflow limitation in the Japanese community.

METHODS

Subjects were recruited through local press advertisement, and 180 individuals were enrolled. Data on age, body mass index (BMI), gender, smoking history, and past medical history were obtained, as were pulmonary function parameters, skeletal muscle mass index, and physical activity.

RESULTS

The final study population comprised 161 participants from whom we obtained valid spirometry results. The mean age of this population was 73.4 ± 4.4 years, and 78 participants (48.4 %) were men. The prevalence of airflow limitation was 29.2 % (n = 47). Subjects with airflow limitation were significantly older (P = 0.01) and had poorer pulmonary function (P < 0.01), lower BMI (P < 0.01), and lower skeletal muscle mass index (P = 0.03) than healthy elderly subjects. Furthermore, skeletal muscle mass index was significantly correlated with the percentage of predicted forced vital capacity (r = 0.45, P < 0.05) and forced expiratory volume in 1 s (r = 0.50, P < 0.05) only in men with airflow limitation.

CONCLUSIONS

We found that the skeletal muscle mass index was significantly reduced in community-dwelling elderly with airflow limitation, and the skeletal muscle mass index was correlated with pulmonary function only in men with airflow limitation.

Effect of a chronic obstructive pulmonary disease (COPD) intervention on COPD awareness in a regional city in Japan

OBJECTIVE

The purpose of this study was to examine the effect of an intervention for chronic obstructive pulmonary disease (COPD) on COPD awareness in a regional city in Japan.

METHODS

Self-administered questionnaires were completed by the residents of the city of Matsuura, Japan. Residents (≥50 years) of the mainland in Matsuura were included in a COPD intervention project (mainland group), while residents of the islands district received no intervention due to geographical issues (island group). The rates of COPD awareness and accuracy of responses to the questions about COPD were compared between the two groups.

MATERIALS

The study included 5,891 residents 40 to 74 years of age of Matsuura in 2013. The mainland group comprised 4,419 subjects, and the island group 1,472 included subjects.

RESULTS

The overall response rate to the questionnaire was 24.6%, with similar response rates between the two groups. The rate of COPD awareness in the mainland group was 24.5%, which was significantly higher than that observed in the island group (11.8%) (p<0.01). The rate of awareness tended to decrease in association with increasing age. Among 276 responders who stated they were aware of COPD, the accuracy rate for responses to the questions about COPD was not significantly different between the groups.

CONCLUSION

In the present study, there was a difference in COPD awareness between the two groups, suggesting that COPD interventions may increase awareness of the disease. However, the level of knowledge regarding COPD remained low and modifications to the intervention are required to improve awareness of the condition, especially among elderly subjects.