Incidence and predictors for hip fracture in people with intellectual disability

Context: In current guidelines, patients with intellectual disabilities (ID), including Down’s Syndrome (DS) are
not recognised as at high risk of osteoporosis, despite some evidence of increased fracture rates and
decreased bone mineral density.

Objective: To investigate the incidence and predictors of hip fractures in patients with ID.

Study design: Retrospective analysis including a cohort study.

Dataset: The Clinical Practice Research Datalink (CPRD), a large UK primary care database, with linkage to
Hospital Episode Statistics (HES).

Population studied: 39,037 people aged 30-79 with intellectual disability (ID), of whom 3,915 with DS, and age
and sex matched controls.

Outcome measures: Incidence of major osteoporotic and hip fracture; hazard ratios for potential risk factors for
hip fracture.

Results: 39,073 patients were identified, of whom 3,915 with DS. Median (10th-90th centile) age at entry was
39.2 (30-61.8) years. 56.7% were men, 20.6% had epilepsy (vs 1.2% in the controls). In patients with ID and
controls respectively, incidence rate (95% CI) of major osteoporotic fracture (vertebra, wrist, shoulder, hip) was
45.7 (43.0-48.5) vs 24.2 (22.3-26.3) /10,000 person-years and of hip fracture 15.6 (14.0-17.3) vs 4.6 (3.8-
5.5)/10,000 person-years. Hip fracture represented 35.8% of all major osteoporotic fractures in the ID vs
22.4% in the control group. Independent predictors of hip fracture (HR [95% CI]) within the ID group included
age (2.31 [2.06 -2.60] in females, 2.08 [1.86-2.33] in males for each ten-years increase); previous osteoporotic
fracture (1.89 [1.37-2.61]); previous other fracture (1.44 [1.08-1.91]); history of falls (1.75 [1.26-2.43]); epilepsy
(1.89 [1.49-2.40]); diabetes (1.55 [1.08-2.23]); Down’s syndrome (1.93 [1.30-2.87]). Higher BMI predicted a
lower risk (0.79 [0.70-0.89] for each 5 points increase).

Conclusion: Patients with intellectual disabilities are at high risk for major osteoporotic fractures, particularly
hip fractures. This finding, from the largest cohort of ID and DS patients ever studied, requires that current
guidelines be revised, and measures introduced to address bone health and reduce fracture risk in this
population.