Box 1.

The PRISM risk stratification tool.

Overview
PRISM generates a predicted risk score (out of 100%) of emergency admission to hospital for each patient on a practice list that is updated monthly. It stratifies:

  • the general practice population into four levels, based on the individual patient’s risk of an emergency admission to hospital in the following 12 months; and

  • patients into four risk groups according to the relative risk within the practice as a whole, regardless of individual characteristics and comorbidities (default stratification).


As an example, using the default stratification, the 0.5% of patients at highest practice risk will appear in level 4; those in the next 4.5% in level 3 (moderate risk); those in the next 15% in level 2 (low risk), and the remaining 80% in level 1 (very low risk).36 The variables used to develop PRISM were drawn from routinely available data on inpatient, outpatient, and primary care episodes, and from the Welsh Index of Multiple Deprivation, which includes data on employment, income, housing, environment, education, and health.
Support and training
GPs were invited to a practice-based training session on using PRISM to identify patients at risk of emergency admission. A user-friendly handbook was provided, along with access to clinical support through two locally appointed GP champions; technical support was delivered via email or telephone to the Primary Care Service Desk of NHS Wales Informatics Service. Individual practices were advised that they could choose how to use the tool in their practice — for example, how often they interrogated the data; whether they reviewed all patients or subgroups, such as risk levels or diagnosed conditions; whether they accessed a patient’s risk score during a consultation; and what action they took based on a patient’s risk score. Each practice nominated a GP lead, who was responsible for coordinating the use of PRISM and the participation in PRISMATIC, including engagement with other clinical and practice staff.

  • PRISM = Predictive Risk Stratification Model. PRISMATIC = Predictive RIsk Stratification Model: A Trial In primary Care.