The incidence of delirium associated with orthopedic surgery: a meta-analytic review.
BACKGROUND
The aim of this study was to perform a systematic review and meta-analysis of the literature regarding the incidence of delirium following orthopedic surgery.


METHODS
Relevant papers were sourced from online databases and gray literature. Included studies used a validated diagnostic method to measure the incidence of delirium in a prospective sample of adult/elderly orthopedic patients. Data were subject to meta-analysis after stratification by type of surgery (elective v. emergency) and inclusion/exclusion of pre-existing cognitive impairment. A funnel plot assessed for publication bias.


RESULTS
26 publications reported an incidence of postoperative delirium of 4-53.3% in hip fracture samples and 3.6-28.3% in elective samples. Significant heterogeneity was evident, and this persisted despite stratification. Hip fracture was associated with a higher risk of delirium than elective surgery both when the cognitively impaired were included in the sample (random effects pooled estimate = 21.7% [95% CI = 14.6-28.8] vs. 12.1% [95% CI = 9.6-14.6]), and when the cognitively impaired were excluded (random effects pooled estimate = 25% [95% CI = 15.7-34.7] vs. 8.8% [95% CI = 4.1-13.6]). The funnel plot showed a deficit of small studies showing low risk and large studies showing high risk. In eight hip fracture studies, the proportion of delirium cases with a preoperative onset ranged from 34 to 92%.


CONCLUSIONS
Delirium occurs more commonly with hip fracture than elective surgery, and frequently has a preoperative onset when associated with trauma. Recommendations are made with the aim of standardizing future research in order to further explore and reduce the heterogeneity and possible publication bias observed.
Bruce
Angela J
AJ
Waitemata District Health Board, Auckland, New Zealand. angela.bruce@waitematadhb.govt.nz
Ritchie
Craig W
CW
Blizard
Robert
R
Lai
Rosalind
R
Raven
Peter
P
D000368:Aged; D003072:Cognition Disorders / Q000453:epidemiology; D003693:Delirium / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology*; D006620:Hip Fractures / Q000453:epidemiology / Q000601:surgery; D006801:Humans; D015994:Incidence; D019637:Orthopedic Procedures / Q000523:psychology* / Q000706:statistics & numerical data*