Epidemiologic characteristics and antibiotics usage pattern of acute pyelonephritis in Korea, 2010-2014: population-based study

Abstract

Background: Acute pyelonephritis is one of the most common community-acquired bacterial infections and its antimicrobial resistance has been rising gradually. Thus, changing pattern of epidemiologic characteristics and antibiotic prescription is expected.

Material and methods: All national health insurance claim data for patients aged ≥15 from 2010 through 2014, which includes ICD-10 codes N10 (acute tubulo-interstitial nephritis) and/or N12 (tubulo-interstitial nephritis, not specified as acute or chronic) as primary discharge diagnosis were obtained from the Health Insurance Review and Assessment Service. Two or more claims during a 14-day period were considered a single event.

Results: There were 151,380 events for acute pyelonephritis in 2010, 157,353 in 2011, 168,470 in 2012, 175,208 in 2013, and 193,245 in 2014. The overall annual incidence rate (per 10,000 populations) of pyelonephritis during 2010-2014 was 39.1 and was on increase from year to year (P <0.001). Approximately eleven times more female patients were suffered from acute pyelonephritis than male patients (males, 6.5 VS. females, 71.3); one of every 4.1 patients was hospitalized (inpatients, 9.6 VS. outpatients, 29.4). Incidence rate increased with age (P <0.001) and was higher in the summer season (P <0.001). Overall recurrence rate was 15.8% and median duration from sporadic event to first recurrence was 44 days. The probability of recurrence increased with the number of previous recurrence. The gross costs of pyelonephritis were 60,178 million won in 2010, 64,419 million won in 2011, 66,707 million won in 2012, 70,461 million won in 2013, and 78,297 million won in 2014. The average medical costs per event were approximately 12.8 times higher in inpatients than outpatients (inpatients, 1,316,000 won VS. outpatients, 103,000 won). The average costs per inpatient episode tend to be higher in elderly population, patients with medical aid, tertiary hospital, and department of internal medicine. The average hospitalization duration per event was 9.0 days; the average number of visits per event was 2.2. The annual overall trends of admission or visit days remained stable throughout the study period (inpatient, P =0.466; outpatient, P =0.080). The average amount of antibiotic consumption per inpatient event was 11.3 DDD and had increased throughout the study period (P =0.002); the average amount of antibiotic consumption per outpatient event was 6.0 DDD and no significant trend was observed (P =0.066). For inpatients, 3rd generation cephalosporin (41.4%) was most commonly prescribed, followed by fluoroquinolone (28.5%). In contrast, fluoroquinolone (54.8%) was the major prescribed antibiotics at outpatient department, followed by 3rd generation cephalosporin (13.1%). Significantly increasing trends from year to year were observed in 3rd generation cephalosporin (P <0.001), beta-lactam/beta-lactamase inhibitor (P =0.007), and carbapenem (P <0.001) among inpatients while decreasing trends were observed in aminoglycoside (P =0.004) and fluoroquinolone (P =0.010). Parenteral antibiotic consumption had increased throughout the study period among inpatients (P <0.001)

Conclusions: In Korea, both annual incidence rate and average costs per event of pyelonephritis were on increase. Significantly increasing trends from year to year were observed in broad-spectrum antibiotic consumption such as 3rd generation cephalosporin, beta-lactam/beta-lactamase inhibitor, and carbapenem as well as parenteral antibiotic consumption among hospitalized patients with acute pyelonephritis. We believe that the present study will play an important role in implementing national health policies including antimicrobial stewardship in terms of offering basic data.