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Epidemiology of Developmental Dysplasia of the Hip: Analysis of Japanese National Database

Hiroki Den1, Junichi Ito2, Akatsuki Kokaze1

  • 1Department of Hygiene, Public Health, and Preventative Medicine, Showa University School of Medicine.

Journal of Epidemiology
|August 12, 2021
PubMed

Insights

The nationwide incidence of developmental dysplasia of the hip dislocation (DDH-dislocation) in Japan is 0.076%. This study found similar rates across regions, but higher risks for infants born in colder months and for girls.

Area of Science:

  • Pediatric Orthopedics
  • Public Health
  • Epidemiology

Background:

  • Developmental dysplasia of the hip (DDH) encompasses hip development disorders in infants.
  • The incidence of DDH-related dislocation (DDH-dislocation) is not well-established nationwide in Japan.
  • Previous estimates for DDH-dislocation range from 0.1-0.3%.

Purpose of the Study:

  • To determine the nationwide incidence of DDH-dislocation in Japan.
  • To investigate regional variations in DDH-dislocation incidence across Japan.
  • To identify risk factors associated with DDH-dislocation.

Main Methods:

  • Retrospective birth cohort study utilizing the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB).
  • Data extracted for patients born between 2011-2013 diagnosed with DDH-dislocation codes (2011-2018).
  • Patients undergoing treatment for DDH-dislocation defined the study cohort.

Main Results:

  • The nationwide incidence of DDH-dislocation was 0.076% across the 2011-2013 birth cohorts (2,367 cases).
  • Incidence rates showed minimal regional variation across Japan.
  • Higher risk observed for infants born in colder months (RR=1.89) and for girls (approx. 7x higher risk).
  • 11.5% of patients were diagnosed at age 1 year or older.

Conclusions:

  • This study provides the first nationwide incidence of DDH-dislocation in Japan at 0.076%.
  • Regional variations in incidence are clinically insignificant.
  • Seasonal birth (colder months) and female sex are significant risk factors for DDH-dislocation.
Abstract

Keywords:
DDHdevelopmental dysplasia of the hipepidemiologyincidence ratenational database

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