Format

Send to

Choose Destination
See comment in PubMed Commons below
Stroke. 2010 Mar;41(3):510-5. doi: 10.1161/STROKEAHA.109.571703. Epub 2010 Jan 14.

Validity of proxies and correction for proxy use when evaluating social determinants of health in stroke patients.

Author information

1
University of Michigan Medical School, Ann Arbor, Mich, USA.

Abstract

BACKGROUND AND PURPOSE:

The purpose of this study was to evaluate stroke patient-proxy agreement with respect to social determinants of health, including depression, optimism, and spirituality, and to explore approaches to minimize proxy-introduced bias.

METHODS:

Stroke patient-proxy pairs from the Brain Attack Surveillance in Corpus Christi Project were interviewed (n=34). Evaluation of agreement between patient-proxy pairs included calculation of intraclass correlation coefficients, linear regression models (ProxyResponse=alpha(0)+alpha(1)PatientResponse+delta, where alpha(0)=0 and alpha(1)=1 denotes no bias) and kappa statistics. Bias introduced by proxies was quantified with simulation studies. In the simulated data, we applied 4 approaches to estimate regression coefficients of stroke outcome social determinants of health associations when only proxy data were available for some patients: (1) substituting proxy responses in place of patient responses; (2) including an indicator variable for proxy use; (3) using regression calibration with external validation; and (4) internal validation.

RESULTS:

Agreement was fair for depression (intraclass correlation coefficient, 0.41) and optimism (intraclass correlation coefficient, 0.48) and moderate for spirituality (kappa, 0.48 to 0.53). Responses of proxies were a biased measure of the patients' responses for depression, with alpha(0)=4.88 (CI, 2.24 to 7.52) and alpha(1)=0.39 (CI, 0.09 to 0.69), and for optimism, with alpha(0)=3.82 (CI, -1.04 to 8.69) and alpha(1)=0.81 (CI, 0.41 to 1.22). Regression calibration with internal validation was the most accurate method to correct for proxy-induced bias.

CONCLUSIONS:

Fair/moderate patient-proxy agreement was observed for social determinants of health. Stroke researchers who plan to study social determinants of health may consider performing validation studies so corrections for proxy use can be made.

PMID:
20075348
PMCID:
PMC2838184
DOI:
10.1161/STROKEAHA.109.571703
[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Support Center