The annual prevalence and incidence rates of idiopathic pulmonary fibrosis (IPF) increased drastically in Korea from 2011 to 2019, with higher rates occurring in men compared with women, researchers reported in BMC Pulmonary Medicine.

The retrospective cohort study investigated changes in the prevalence and incidence of IPF over time in Korea, as well as comorbidities and treatments commonly associated with IPF, using nationwide health claims data between 2011 and 2019 from the database of the Korean Health Insurance Review and Assessment (HIRA). Eligible participants made at least 1 claim per year for IPF.

The patients were compared by age (<70 vs ≥70 years), sex, Charlson comorbidity index (CCI; 0-3 vs ≥4), and pirfenidone use (>3 months [pirfenidone user group] and <3 months or not treated with pirfenidone [pirfenidone nonuser group]).

The annual prevalence rate for IPF increased from 7.50 to 23.20 per 100,000 persons, and the annual incidence rate increased from 3.56 to 7.91 per 100,000 person-years from 2011 to 2019 in the Korean population. The IPF prevalence and incidence rates were more than twice as high in men as in women since 2011. For example, in 2019, the incidence rate per 100,000 person-years in men was 11.81 vs 4.02 in women.

Many patients with IPF had respiratory and nonrespiratory comorbidities, although the prevalence was dependent on sex, age, and use of pirfenidone.

Comorbidity prevalence was assessed in 21,111 patients with IPF according to age and sex. In all subgroups, chronic obstructive pulmonary disease (COPD) was the most common respiratory comorbidity (37.34%), followed by lung cancer (3.34%). The most common nonrespiratory comorbidities were gastro-esophageal reflux disease (GERD, 70.83%), dyslipidemia (62.93%), and hypertension (59.04%).

COPD and lung cancer occurred more frequently in men vs women (COPD: 40.58% vs 29.32%; lung cancer; 4.11% vs 1.45%) and pulmonary hypertension was more prevalent in women vs men (2.43% vs 1.11%). The rates of diabetes mellitus and ischemic heart disease were increased in men, and those of GERD, anxiety, depression, and congestive heart failure were more common in women. COPD occurred in a higher proportion of patients aged 70 years and older than in those aged less than 70 years (39.39% vs 34.20%).

All nonrespiratory comorbidities except GERD occurred more frequently in patients aged 70 years and older compared with those aged less than 70 years. CCI was greater in men compared with women and higher in patients aged 70 years and older vs those aged less than 70 years.

A greater percentage of men and patients aged 70 years and older were found among the patients using pirfenidone vs among patients not using the drug. The proportion of patients with lung cancer was also greater among patients who received pirfenidone, and the proportion of pulmonary embolism and pulmonary hypertension was higher among untreated patients.

Patients with high CCI used more medical resources associated with admission within 90 days, and the low burden group used more resources associated with outpatient clinics. At 90 and 365 days, the total medical costs were higher in patients with high CCI vs low CCI.

Among several limitations, IPF was defined according to the 10th revision of the International Statistical Classification of Diseases and Related Health Problems code at the time of diagnosis, and a limited number of baseline characteristics were assessed. In addition, the only antifibrotic agent included in the study was pirfenidone.

“Many patients with IPF had respiratory and nonrespiratory comorbidities, although the prevalence was dependent on sex, age, and use of pirfenidone,” stated the researchers. “The prevalence of these comorbidities was higher 3 years after than at the time of IPF diagnosis and affected the use of pirfenidone and medical resources.”

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