Impact case study database

Impact on clinical guidelines: SNAP was added to TOXBASE

The UK’s primary clinical guidelines for treating all poisoning cases are published by the National Poisons Information Service (NPIS; the National Institute for Health and Care Excellence guideline on poisoning redirects to the NPIS website). NPIS maintains an online clinical toxicology database TOXBASE and its associated smartphone application, which is available to all clinicians in the UK and had 12,015 subscribers in 2018 [5.1]. On the 15^th of April 2020, the SNAP regimen was added to TOXBASE as a protocol option for treating paracetamol overdose [5.2].

Impact on clinical practice

Following the update to TOXBASE, the SNAP regimen is now available to treat all cases of paracetamol overdose presenting at any UK hospital. Between the update on the 15^th of April and the end of the REF period on the 31^st of the December 2020, the SNAP dosing section of TOXBASE was accessed 3,913 times from 185 hospitals across the UK [5.3a, b, e]; the locations of accesses are illustrated below in Figure 1. In addition, within the same time period, the SNAP entry was accessed 162 times from 14 overseas countries, including the Republic of Ireland, Brazil, Australia, Poland and the Czech Republic [5.3c–e].

It is important to note that the number of accesses to the TOXBASE site is a significant underestimation of the true number of times the regimen has been used to treat a patient. Many hospitals produce hard copies of protocols for their staff to refer to and, once healthcare professionals have become accustomed to using the regimen, they may not need to log into the database each time they use it. For example, the Royal Infirmary of Edinburgh has accessed the SNAP page on TOXBASE only 3 times since it became live, but has used the regimen to treat all 412 paracetamol overdoses seen in that time [5.3e].

Figure 1.

Geographical spread of UK hospitals who have accessed the SNAP page of TOXBASE between the 15^th of April and the 31^st of December 2020

Source: NPIS [5.3]

By summer 2020, the SNAP regimen was in routine use in 100% of hospitals in mainland Scotland, and thus is being used to treat all approximately 5,700 annual admissions for paracetamol overdose in Scotland [5.4]. A consultant in the Greater Glasgow and Clyde health board noted: “ Since [summer 2020], it's been very successful. The juniors and nursing staff prefer using it and patients have a shorter length of stay and fewer adverse reactions.” [5.4c].

Notably, 11 hospitals serving major UK cities including Manchester, Bristol and Nottingham had already adopted the SNAP regimen prior to the TOXBASE update. First among these were the Royal Infirmary of Edinburgh (September 2015), St Thomas’ Hospital London (June 2016) and Royal Victoria Infirmary in Newcastle (October 2016); these 3 hospitals had by June 2018 treated a combined 2,246 patients according to the SNAP regimen [3.3]. They were followed by the Pennine Acute Hospital (serving Manchester; December 2018), North Bristol (May 2018), City Hospital Birmingham (summer 2019), Barnsley Hospital (December 2018), Chesterfield Royal Hospital (August 2018), Derby Royal (August 2018), Crosshouse Hospital Kilmarnock (summer 2019) and NHS Highland (summer 2019) [5.5].

Impact on health & welfare

Since the SNAP regimen reduces the rate of ADRs from 11% of patients to 2% [3.3] its adoption means that patients are less likely to experience highly unpleasant episodes of nausea, vomiting and anaphylactoid reactions. Thus, if the 3,913 UK accesses to the SNAP entry on TOXBASE each represented the presentation in the Emergency Department of a single patient, approximately 78 of these would have ADRs when treated with the SNAP regimen, whilst 430 patients would have experienced ADRs had they been treated with the 21-hour regimen instead. Thus, ADRs were averted in 352 patients in this calculation alone. The true number of averted ADRs will be significantly higher, given that clinicians do not need to access TOXBASE to use the SNAP regimen every time an overdose presents, but will likely refer to a printed copy kept in the Emergency Department.

The averted ADRs not only reduce the distress experienced by patients but also alleviate the additional burden that ADRs place on NHS resources through requiring nursing time to care for unwell patients and administer antihistamines.

Economic impact: Use of SNAP reduces length of hospital stay

Use of the SNAP regimen saves NHS resources through shortening the length of time patients stay in hospital. A formal health economic assessment was undertaken to quantify this reduction. The assessment used data from a clinical audit of all admissions for paracetamol overdose at the Royal Infirmary of Edinburgh, and compared two time periods: before the SNAP regimen was introduced (29^th December 2014 to 26^th September 2015, n=373), and after SNAP was introduced (27^th September 2015 to 26^th June 2016, n=450) [5.6]. Pricing categories based on Health Resource Group codes were assigned to patients depending on length of stay and presence or absence of adverse events.

This assessment found that the 21-hour regime was associated with more patients staying in hospital for longer than 24 hours (the threshold typically used to denote “long stay”; Figure 2 [5.6]). Together with a lower number of adverse events recorded, the shorter length of stay associated with the SNAP regimen was found to lead to an estimated saving of GBP180.33 per patient. Extrapolating this to the approximately 50,000 patients treated annually in the UK [5.7], suggests that, once implemented at a national scale, use of the SNAP regimen could result in NHS savings of up to GBP9,016,000 every year [5.6].

Figure 2: Length of hospital stay in patients treated with SNAP (orange) versus patients treated with the 21-hour regime (blue). Approximately 2/3 of the 21-hour regimen group exceeded the 24-hour threshold stay typically used to denote a “long stay”, compared with only 1/5 in the SNAP group [5.6].