Utility of the Hospital Frailty Risk Score Derived From Administrative Data and the Association With Stroke Outcomes
Authors: Kilkenny Monique F. , Phan Hoang T. , Lindley Richard I. , Kim Joosup , Lopez Derrick , Dalli Lachlan L. , Grimley Rohan , Sundararajan Vijaya , Thrift Amanda G. , Andrew Nadine E. , Donnan Geoffrey A. , Cadilhac Dominique A. , Anderson Craig , Bernhardt Julie , Bew Paul , Bladin Christopher , Cadigan Greg , Castley Helen , Lee Andrew , Mackay Mark , Martyn Sandra , McNeil John , Middleton Sandy , Pollack Michael , Simcocks Mark , Simmonds Frances , Dewey Helen , Faux Steven , Hill Kelvin , Levi Christopher , Price Christopher , Bambery Pradeep , Bates Tim , Beltrame Carolyn , Blacker David , Butler Ernie , Butler Sean , Crompton Douglas , Crosby Vanessa , De Wytt Carolyn , Douglas David , Dunlop Martin , Easton Paula , Ermel Sharan , Gange Nisal , Geraghty Richard , Gill Melissa , Hall Graham , Hand Peter , Herkes Geoffrey , Hines Karen , Hishon Francis , Hughes James , Iedema Joel , Jude Martin , Kraemer Thomas , Laird Paul , Madden Johanna , Mahaffey Graham , Milosevic Suzana , O’Brien Peter , Read Stephen , Rowe Kristen , Ryan Fiona , Sabet Arman , Saines Noel , Salud Eva , Siller Amanda , Staples Christopher , White Richard , Wong Andrew , Armstrong Robin , Churilov Leonid , Dias Alison , Gibbs Adele , Grabsch Brenda , Kung Francis , Lim Joyce , Moss Karen , Paice Kate , Salama Enna , Small Sabrina , Stojanovic Renee , Street Steven , Tod Emma , Wallis Kasey 
Published: June 2021

Background and Purpose:
Conditions associated with frailty are common in people experiencing stroke and may explain differences in outcomes. We assessed associations between a published, generic frailty risk score, derived from administrative data, and patient outcomes following stroke/transient ischemic attack; and its accuracy for stroke in predicting mortality compared with other measures of clinical status using coded data.

Methods:

Patient-level data from the Australian Stroke Clinical Registry (2009–2013) were linked with hospital admissions data. We used
International Statistical Classification of Diseases and Related Health Problems, Tenth Revision
codes with a 5-year look-back period to calculate the Hospital Frailty Risk Score (termed Frailty Score hereafter) and summarized results into 4 groups: no-risk (0), low-risk (1–5), intermediate-risk (5–15), and high-risk (>15). Multilevel models, accounting for hospital clustering, were used to assess associations between the Frailty Score and outcomes, including mortality (Cox regression) and readmissions up to 90 days, prolonged acute length of stay (>20 days; logistic regression), and health-related quality of life at 90 to 180 days (quantile regression). The performance of the Frailty Score was then compared with the Charlson and Elixhauser Indices using multiple tests (eg,
C
statistics) for predicting 30-day mortality. Models were adjusted for covariates including sociodemographics and stroke-related factors.

Results:

Among 15 468 adult patients, 15% died ≤90 days. The frailty scores were 9% no risk; 23% low, 45% intermediate, and 22% high. A 1-point increase in frailty (continuous variable) was associated with greater length of stay (OR
adjusted
, 1.05 [95% CI, 1.04 to 1.06), 90-day mortality (HR
adjusted
, 1.04 [95% CI, 1.03 to 1.05]), readmissions (OR
adjusted
, 1.02 [95% CI, 1.02 to 1.03]; and worse health-related quality of life (median difference, −0.010 [95% CI −0.012 to −0.010]). Adjusting for the Frailty Score provided a slightly better explanation of 30-day mortality (eg, larger
C
statistics) compared with other indices.

Conclusions:
Greater frailty was associated with worse outcomes following stroke/transient ischemic attack. The Frailty Score provides equivalent precision compared with the Charlson and Elixhauser indices for assessing risk-adjusted outcomes following stroke/transient ischemic attack.