Prediction of mortality in elderly patients with hip fractures: a two-year prospective study of 1,944 patients

Abstract

Background: Hip fracture patients are reported to have an increased mortality rate compared to the general population. In order to be able to reduce the morbidity and mortality after a hip fracture, our efforts to identify the patients at risk already upon admission to the hospital need to be increased. For such a risk assessment, robust, validated, and reproducible criteria are mandatory.

Objective: To determine preoperative factors associated with mortality and to evaluate the combined use of the American Society of Anesthesiologists (ASA) and the Short Portable Mental Status Questionnaire (SPMSQ) to identify patients with an increased mortality rate and to create a predictive model to assess the mortality risk after hip fracture surgery.

Methods: A total of 1,944 consecutive patients aged 66 years or older admitted for a hip fracture were included in a prospective cohort study with a 24-month follow-up. The patients were assessed with regard to gender, age, type of hip fracture, smoking habits, comorbidities, general physical health according to the ASA classification, and cognitive function according to the SPMSQ. A higher ASA score indicates an increasingly severe systemic disease and a lower SPMSQ score indicates an increasingly severe cognitive dysfunction. We used Cox proportional hazard models and classification trees to identify the factors associated with mortality. The predictive model was created based on factors that were significantly associated with death and all readily accessible upon admission.

Results: The mortality rate during the acute hospitalization period was 4%, at 4 months 16%, and at 24 months 38%. The most prominent factors associated with mortality were high ASA scores, low SPMSQ scores, high age and male gender. The SPMSQ score provided additional information about the survival time, compared to when the ASA score was used alone.

Conclusion: The combined use of the ASA classification for assessing physical health and the SPMSQ for assessing cognitive function effectively identified hip fracture patients with an increased mortality rate. We present a predictive model including age, gender, ASA, and SPMSQ that can be used to assess the mortality risk after hip fracture surgery.