mSOAR: an effective bedside stroke prognosis tool

Discussion

This study has shown that in our population of patients admitted to Princess of Wales Hospital, Bridgend, the mSOAR score is an excellent predictor of moderate-severe disability (mRS≥4) and mortality as shown from ROC curve results. Therefore, its use as part of acute stroke admission would enable more informed admission prognostic discussions and earlier multidisciplinary discharge planning meetings. Accelerating discharge planning could aid time efficient transfer of patients to appropriate locations, eg to a rehabilitation unit or to home with early supported discharge team input. Not only will this be of benefit to those affected but also to patient flow, thus enabling more appropriate and effective use of inpatient stroke service resources. However, we recognise that for time efficient transfer of patients there needs to be an increase in community resources as well as a cultural change away from delaying the discharge process until patients are ‘medically stable for discharge’.

Our results show that recovery to discharge with moderate-severe disability (mRS 4–5) takes significantly longer than those with mild-moderate disability (mRS 0–3). As such, the mSOAR criteria could enable earlier prediction of discharge disability. This in turn can enable initiation of the discharge process earlier with the potential to dramatically shorten number of days in the acute stroke unit. There are a multitude of benefits to this, including earlier rehabilitation in the community and reduced hospital-acquired infections.

The mSOAR could miss some patients who may deteriorate unexpectedly following admission (eg haemorrhagic transformation or secondary pneumonia)¹⁰ as well as others improving despite severe infarct or haemorrhage. Therefore, we would advise that no prognostic tool should be used as the sole basis of management decisions.

The components of the mSOAR have been widely shown to be predictors of outcome. They are stroke type, anatomical location (Oxford Community Stroke Project classification), age, pre-stroke disability (mRS) and stroke severity (NIHSS).^11–19 In addition to combining these elements, it has also been validated in both ischaemic and haemorrhagic strokes, unlike other current prognostic tools, thus making it easier to integrate into clinical practice.

One perceived limitation of the mSOAR scoring system in this study is that we have used the mRS score as a marker of disability despite it being a component of the mSOAR scoring system. The mRS score is an indicator of a person's level of dependence, a marker of frailty. It has previously been shown to be a predictor of patient outcomes, including mortality.^8,20 Therefore, it follows that a patient admitted dependent for all ADLs is not going to be discharged independent and is closer to the mortality end of the outcome spectrum. Our results are significant when comparing mSOAR to change in mRS. A healthy, symptom-free person who dies would have an mRS change of 6 and a fully dependent person who dies a change of only 1. We conclude that the pre-stroke mRS is of value in predicting post-stroke disability but cannot independently account for why we have found the mSOAR score to be such an effective predictor of discharge disability; rather, this is likely to be due to the combination of components.

Interestingly, 5% of our study population had better discharge disability than pre-stroke disability. This may be attributable to patients with minor strokes having other problems limiting independence that were addressed effectively during their time on the stroke ward.

Limitations of this project are that there were no patients with either a minimum mSOAR score of 0 or the maximum of 9, most likely because the former's mild symptoms and preadmission mortality for the latter. The disability on discharge was not assessed as to its correlation with place of discharge because of multifactorial reasons for the latter, such as family social support. Although this was a single-centre study, our results are in keeping with previous SOAR and mSOAR research that was assessed in over 14,000 patients. They showed an auROC of 0.79 (0.78–0.80)⁸ and auROC 0.83 (0.79–0.86),⁹ respectively, for inpatient mortality prediction; therefore, they have good accuracy. We would recommend further research into mSOAR score's ability to predict other post-stroke outcomes such as cognition, mood and communication as then the appropriate therapy could be better targeted in the hyperacute and acute settings. Our findings should also be replicated in different ethnic populations and independent datasets.