Association between Norton Scale Score and Long-term Mortality after Acute Myocardial Infarction

Background: there are several factors associated with long-term mortality after Acute Myocardial Infarction (AMI), one of which is the patient’s basic physical and mental functions. In order to estimate these functions, Norton scale (NS) is recommended as an assessment tool. This scale, routinely used to estimate risk of pressure ulcers, contains 5 domains: mental condition, physical condition, mobility, activity in daily living (ADL) and incontinence. Each domain graded from 1 (poorest) to 4 (best) condition.

Objective: to determine whether NS (domains and total score) are associated with long-term mortality after AMI.

Methods: a retrospective study based on computerized medical records of AMI patient hospitalized in Soroka Medical Center in 2004-2012. In addition to the NS parameters during the hospitalization, personal patients’ characteristics were collected: socio-demographics, cardiovascular risk factors and other comorbidities, AMI type and hospitalization characteristics.

Outcome: all cause long-term (up to 10 years) mortality.

Results: 6,964 patients (mean age 67.3±14.1 years, 68.1% males and 10% Bedouins) were included. Common domain score was 4; mean total score 17.8±3; 78.9% of patients performed high NS (using the cut-off point of 16). The latter were younger and showed lower prevalence of cardiovascular risk factors and other comorbidities. Throughout the follow-up 2,651 (38.1%) patients died. Low total NS (≤16) was independently related to the outcome (AdjHR=1.66; p<0.001). Grades lower than 4 in three domains were inversely related to the outcome: physical condition (AdjHR=1.21), mobility (AdjHR=1.15) and ADL (AdjHR=1.15); (p

Conclusions: NS score is an independent prognostic factor of long-term mortality following AMI. Routinely assessing NS in AMI patients as a basic functional tool could be added to the orthodox cardiovascular and comorbidities prognostic scales. The NS be fundamental criteria in prognostic evaluation of individualized and comprehensive rehabilitation program.