Five-year risk of fracture and subsequent fractures among adults with cerebral palsy

Abstract

Background: Epidemiologic evidence documenting the incidence of fracture and subsequent fractures among adults with cerebral palsy (CP) is lacking, which could inform fracture prevention efforts. The objective was to characterize the 5-year rate of initial and subsequent fragility fractures among adults with CP.

Methods: This retrospective cohort study used Medicare claims from 01/01/2008-12/31/2019 from adults ≥18 years old with CP (n = 44,239) and elderly ≥65 years old without CP (n = 2,176,463) as a comparison. The incidence rate (IR), IR ratio (IRR), and site distribution were estimated for the initial and subsequent fragility fractures over 5-years by sex and age.

Results: The IR of fragility fracture at any site over the 5-year follow-up was similar for 18-30-year-old men with CP (IR = 5.2; 95%CI = 4.4-5.9) and 30-34-year-old women with CP (IR = 6.3; 95%CI = 5.3-7.2) compared to the same sex youngest-old (65-74 years old) without CP (IRR = 1.09 and 0.94, respectively, both P > 0.05), and increased with older age for those with CP. The number of fragility fractures and IR of subsequent fragility fractures was similar for young men and middle-aged women with CP compared to elderly without CP, and increased with older age for those with CP. The proportion of fragility fracture at the tibia/fibula decreased while the vertebral column and multiple simultaneous sites (most involved hip/lower extremities) increased with older age.

Conclusion: Young and middle-aged adults with CP had similar-to-worse initial and subsequent fragility fracture profiles compared to the general elderly population- a well characterized group for bone fragility. Findings emphasize the need for fracture prevention efforts at younger ages for CP, possibly by ~5 decades younger.

Keywords: CI, confidence interval; CP, cerebral palsy; Cerebral palsy; Fracture; ICD, International Classification of Diseases, Ninth or Tenth Revision, Clinical Modification; IR, incidence rate; IRR, incidence rate ratio; Prevention; Subsequent fracture.

Fig. 1

Flow chart of inclusion/exclusion criteria to derive the analytic samples of adults with cerebral palsy (CP) and elderly without CP.

Fig. 2

Incidence rate (IR) of fragility fracture at any site over a 5-year follow-up for (A) women with cerebral palsy (CP) vs. elderly women without CP and (B) men with CP vs. elderly men without CP by age group. The circle represents the IR estimate and the vertical lines represent the 95 % confidence interval. The 95 % confidence intervals are very small for elderly women and men without CP and difficult to visualize. The horizontal dashed red lines represent the IR for the 3 elderly age groups to ease visual comparison for the CP age groups.

Fig. 3

The proportion of adults with cerebral palsy (CP) by young (18–40 years [y]), middle-aged (41-64y), and elderly (≥65y) groups and elderly without CP (w/oCP) with 1 to ≥3 fragility fractures (FFx) over the 5-year follow-up for (A) women and (B) men. For panel A, the 2 and ≥ 3 FFx categories are combined for young women with CP for patient de-identification purposes (n < 11 for one of the categories). *P < 0.05 compared to elderly w/oCP based on the zero-inflated part of the generalized linear model with a zero-inflated Poisson distribution. #P < 0.05 compared to elderly w/oCP based on the count part of the generalized linear model with a zero-inflated Poisson distribution.

Fig. 4

The site distribution of the first fragility fracture for adults with cerebral palsy (CP) by young (18–40 years [y]), middle-aged (41-64y), and elderly (≥65y) groups and elderly without CP (w/oCP) over the 5-year follow-up for (A) women and (B) men. For panel B, the ulna/radius and unspecified categories were combined for young men with CP and the hip and femur categories were combined for elderly men with CP for patient de-identification purposes (n < 11 for one of the categories). *P ≤ 0.001 compared to elderly w/oCP using the Chi-squared test.