Association between Serum IGF-I levels and Postoperative Delirium in Elderly Subjects Undergoing Elective Knee Arthroplasty.

Timothy E Yen,Christopher C Young,Aibek E Mirrakhimov,Sarah K Rivelli,Benjamin J Flink,John C Allen,Stephanie C Patterson,Thomas P Vail,Meredith R Metcalf,Sandhya A Lagoo,Richard E Moon,Madan M Kwatra,Paula T Trzepacz

doi:10.1038/srep20736

Abstract

Evidence is mixed for an association between serum insulin-like growth factor-I (IGF-I) levels and postoperative delirium (POD). The current study assessed preoperative serum IGF-I levels as a predictor of incident delirium in non-demented elderly elective knee arthroplasty patients. Preoperative serum levels of total IGF-I were measured using a commercially available Human IGF-I ELISA kit. POD incidence and severity were determined using DSM-IV criteria and the Delirium Rating Scale-Revised-98 (DRS-R98), respectively. Median IGF-I levels in delirious (62.6 ng/ml) and non-delirious groups (65.9 ng/ml) were not significantly different (p = 0.141). The ratio (95% CI) of geometric means, D/ND, was 0.86 (0.70, 1.06). The Hodges-Lehmann median difference estimate was 7.23 ng/mL with 95% confidence interval (−2.32, 19.9). In multivariate logistic regression analysis IGF-I level was not a significant predictor of incident POD after correcting for medical comorbidities. IGF-I levels did not correlate with DRS-R98 scores for delirium severity. In conclusion, we report no evidence of association between serum IGF-I levels and incidence of POD, although the sample size was inadequate for a conclusive study. Further efforts to investigate IGF-I as a delirium risk factor in elderly should address comorbidities and confounders that influence IGF-I levels.

Highlights

Delirium is characterized by fluctuating disturbances in attention, memory, orientation, perception, psychomotor behavior, and sleep
In order to better understand the relationship between preoperative serum Insulin-like growth factor-I (IGF-I) and postoperative delirium (POD) without the confound of dementia, we prospectively studied 106 healthy, non-demented elderly subjects undergoing elective knee replacement surgery about whom we previously reported a POD incidence of 27%23
The geometric means (GM) ratio and 95% CI for D/ND was 0.86 and (0.70, 1.06) indicating that mean preoperative IGF-I level in delirium subjects was 14% lower

Summary

Introduction

Delirium is characterized by fluctuating disturbances in attention, memory, orientation, perception, psychomotor behavior, and sleep. IGF-I is believed to be neuroprotective, and low IGF-I levels have been associated with aging and Alzheimer’s dementia, both of which are major risk factors for delirium[12,13,14,15]. Three authors have found a significant association between low levels of IGF-I and delirium[18,19,21,22], while three others did not[16,17,20] Potential reasons for this discrepancy include small patient cohorts and different study designs, IGF-I assay methodology, patient exclusion criteria, patient health status (acutely ill vs healthy), and clinical status (postoperative vs medically ill). We previously presented a preliminary analysis of 85 subjects from this cohort that found a statistically significant association between lower preoperative plasma IGF-I levels and increased incidence and severity of POD24.

Methods

Results

Conclusion