Hypoglycaemic emergencies attended by the Scottish Ambulance Service: a multiple methods investigation.

Abstract

Background Changing service demands require United Kingdom ambulance services to redefine their role and response strategies, in order to reduce unnecessary Emergency Department attendances. Treat and Refer guidelines have been developed with this aim in mind. However, these guidelines have been developed in the absence of reliable evidence or guiding mid-range theory. This has resulted in inconsistencies in clinical practice. One condition frequently included in Treat and Refer guidelines is hypoglycaemia. Therefore this thesis aimed to investigate prehospital hypoglycaemic emergencies in order to develop an evidence base for future interventions and guideline development. Research approach A pragmatic and inductive applied health services research approach was employed. Multiple methods were used in a sequential explanatory design. Three linked studies were undertaken with the results of previous studies informing the development of the next. Study one: A scoping review of prehospital treatment of hypoglycaemic events. Aims: i) To describe the demographics of the patient population requiring ambulance service assistance for hypoglycaemic emergencies; ii) To determine the extent to which post-hypoglycaemic patients with diabetes, who are prescribed oral hypoglycaemic agents (OHA), experience repeat hypoglycaemic events (RHE) after being treated in the prehospital environment. Methods: A scoping literature review was conducted using an overlapping retrieval strategy that included both published and unpublished literature. Findings: Twenty-three papers and other relevant material were included. Hypoglycaemia related ambulance calls account for 1.3% to 5.2% of ambulance calls internationally. Transportation rates varied between studies (25%-73%). Repeat hypoglycaemic emergencies are experienced by 2-7% of patients within 48 hours. There was insufficient detail to determine any relationship between repeat events and OHA. The low quality of included papers means that the results should be cautiously interpreted. The safety of leaving patients on OHA at home post hypoglycaemic emergency is unknown. Consequently patients taking OHAs who experience a hypoglycaemic emergency should be transported to hospital for observation. There was a lack of knowledge about the Scottish demographics of the patient population. Study two: A retrospective cross-sectional observational study of diabetes related emergency calls. Aims: To investigate i) the patient demographics and characteristics of hypoglycaemia related emergency calls; ii) the incidence of repeat hypoglycaemic events; and iii) the factors associated with emergency calls that result in individuals being left at home. Methods: A retrospective observational cross-sectional study conducted using Medical Priority Dispatch System® call data from West of Scotland Ambulance Control Centre over a 12 month period. Data were extracted on age, gender, dispatch code, time of call, deprivation category, and immediate outcome (home or hospital). Multiple regression analysis was used to determine predictors of remaining at home. Findings: 1319 calls for hypoglycaemia were received. Patient demographics were similar to the scoping review findings. Most patients remained at home (N = 916 vs N = 380; p < .001). RHE’s were experience by 3.1% within 48 hours, and 10.6% within two weeks. The most significant independent predictor for patients remaining at home was a prior call to the ambulance service (OR of 2.4 [95%CI 1.5 to 3.7]). Patients’ reasons for remaining at home and the causes of subsequent severe events are unknown. It is likely that non-clinical factors may explain some of this behaviour. Study 3: Investigating patients’ experiences of prehospital hypoglycaemic care. Aim: To investigate the experiences of patients who are attended by ambulance clinicians for a hypoglycaemic emergency. Methods: In-depth interviews with adults with diabetes who had recently experienced a hypoglycaemic emergency treated by ambulance clinicians. Participants were recruited from Greater Glasgow and Clyde and Lanarkshire Health Board areas. Data were analysed using Framework Analysis. Findings: Twenty six patients were interviewed. Three key themes were developed. Firstly, an explanation for help seeking behaviour; patients’ impaired awareness of hypoglycaemia as well as the inability of friends and relatives to cope can contribute to an ambulance call-out. Secondly, the perceptions of ambulance service care; patients felt the service provided was good; however ambulance clinicians’ advice was inconsistent. Thirdly, the influences on uptake of follow-up care; patient preferences for follow-up care were influenced by previous experiences of home, hospital and primary care. Post-hoc analysis identified three psychological theories that may explain these findings and provide a useful basis for intervention development: Common Sense Model (Leventhal et al, 1998); Health Belief Model (Rosenstock, 1966); Ley’s cognitive hypothesis model of communication (Ley and Llewelyn, 1995; 1981). Conclusion Most people treated for severe hypoglycaemia by ambulance clinicians remain at home and do not follow-up their care. A few experience repeat hypoglycaemic emergencies. Key causal, but modifiable factors, contributing to this include:- impaired awareness of hypoglycaemia; inconsistent delivery of ambulance clinician referral advice; and patients’ perceptions of the costs and benefits of follow-up care. Ambulance services cannot address all these factors in isolation. The studies in this thesis have generated an evidence base and identified plausible candidate theories. This will support the future development of novel interventions to improve severe hypoglycaemic emergency follow-up.