Impact of a DISN on hypoglycaemia-related hospital admissions

Hypoglycaemia is a side-effect of certain blood glucose-lowering therapies, particularly insulin, although it also occurs as a side-effect of sulphonylurea (SU) therapy (Campbell, 1985; Leese et al, 2003; Bolen et al, 2007), and can be precipitated by factors such as increased alcohol consumption, reduced food intake and concurrent illness.

The DCCT (Diabetes Control and Complications Trial; DCCT Research Group, 1993) in type 1 diabetes and the UKPDS (UK Prospective Diabetes Study; Holman et al, 2008) in type 2 diabetes demonstrated that tight glycaemic control results in a reduced risk of diabetes-related complications. However, in the DCCT there was a three-fold increase in the risk of hypoglycaemia in the intensive control arm compared with the conventional arm (DCCT Research Group, 1993), and similarly, rates of hypoglycaemia were significantly higher in the intensively controlled arm of the UKPDS (UKPDS Group, 1998). These studies demonstrated that tight glycaemic control with insulin or SU therapy was associated an increased risk of hypoglycaemia.

These findings have since been confirmed in more recent studies, including ACCORD (Action to Control Cardiovascular Risk in Diabetes; ACCORD Study Group et al, 2008), ADVANCE (Action in Diabetes and Vascular Disease: Preterax and Diamicron MR-Controlled Evaluation; ADVANCE Collaborative Group et al, 2008) and VADT (Veterans Affairs Diabetes Trial; Duckworth et al, 2009), in which an aggressive approach to achieving tight glycaemic control resulted in an increase in the number of people experiencing hypoglycaemia.

Hypoglycaemia is also the most common reason for people with diabetes to attend an accident and emergency (A&E) department (Holmwood et al, 1992; Goyder et al, 1997). These individuals only make up a small proportion of the total number of people with diabetes who have severe hypoglycaemic episodes as most cases are managed at home by carers (Potter et al, 1982; Frier, 1993; Hart and Frier, 1998; Leese et al, 2003). 

Hypoglycaemia results in a significant negative impact on metabolic control, quality of life and subsequent health outcomes (Campbell, 1985; Davis et al, 2005; Lundkvist et al, 2005). It is also associated with considerable NHS resource use as it results in increased ambulance call-outs, A&E attendances and hospital admissions (Holstein et al, 2002; Lundkvist et al, 2005). Most cases of hypoglycaemia that present to the A&E department are managed without involvement of the diabetes specialist team (Daniels et al, 1999).

In 2006, the authors had the opportunity to improve the diabetes outreach service to the A&E department by increasing provision of diabetes inpatient specialist nurses (DISNs) and ensuring proactive follow-up of people admitted to hospital with hypoglycaemia. The impact of this service was audited to establish its effectiveness.

Methods
The Countess of Chester NHS Foundation Trust is a medium-sized district general hospital serving a population of approximately 14000 people with diabetes. In 2004, a previous departmental audit demonstrated only sporadic contact of DISNs with inpatients presenting to the A&E department with hypoglycaemia, with approximately only one quarter having any contact. Therefore, in 2006, a diabetes outreach service for the A&E department was established. People with diabetes who attended the A&E department with hypoglycaemia were rapidly assessed by a DISN between the hours of 9–5 pm, Monday to Friday. People with diabetes presenting to A&E with hypoglycaemia outside of these times were contacted by the DISN using letters and telephone calls to ensure proactive follow-up.

The interventions used by the DISN included patient education together with adjustment of diabetes-related medications when necessary. The education provided fell into three broad categories – prevention, identification and treatment of hypoglycaemia – with the aim of improving the person’s own awareness to reduce the incidence of hypoglycaemia. Where appropriate, literature was also provided to support the advice given to individuals with diabetes. 

Data were collected for people with diabetes who presented to the A&E department of the Countess of Chester NHS Foundation Trust with hypoglycaemia for the years 2004, 2006 and 2008. These individuals were identified by searching the hospital IT system for people with diabetes who had presented to A&E and were coded as having hypoglycaemia. These data were collected from both the A&E department and nursing and medical notes.

SPSS version 13.0 for Windows was used for all data analyses. The data were first subjected to testing for normality, following which any non-parametric data were subjected to logarithmic conversion. An analysis of variance was used to compare means between the groups. Statistical significance was taken at the 5% level (P<0.05).

Results 
There was a year-on-year increase in the number of people with diabetes presenting to A&E with hypoglycaemia, which resulted in a progressive increase in the number of people seen by DISNs (Table 1). Despite the increase in A&E attendances, there was no simultaneous increase in the number of people admitted to hospital with hypoglycaemia; there were no more in 2008 (six admissions) than in 2004 (seven admissions). There was a small increase in the number of people with diabetes who attended A&E more than once with hypoglycaemia (two people in 2004 vs seven in 2008). 

Each year, people admitted to hospital with hypoglycaemia had significantly lower mean HbA_1c levels (P<0.0001; Table 1) than the previous year. From 2004 to 2006, there was also a significant increase in the use of oral antidiabetes drugs (OADs), insulin, and combinations of insulin and OADs among people presenting to the A&E department with hypoglycaemia (Table 2).

The average age of the people presenting to A&E with hypoglycaemia increased between 2004 and 2006 (P=0.018), however the ages of those attending A&E in 2006 and 2008 did not significantly differ. Individuals admitted to hospital with hypoglycaemia were predominantly male (Table 1).

The factors precipitating hypoglycaemia varied from person to person. These included reduced food intake, increased alcohol consumption, increased activity, concurrent illness, impaired renal or hepatic function, and incorrect dose or time of treatment taken for their diabetes. Each cause was discussed on an individual basis with the person and followed with appropriate education and medication adjustment. 

Discussion
The present study demonstrates the effectiveness of improving the liaison between DISNs and the A&E department in preventing hospital admissions of people with hypoglycaemia.

There was no rise in the number of hypoglycaemia-related hospital admissions from 2004 to 2008 despite increasing numbers of A&E attendances.

Previous research has shown that the management of people presenting to A&E with hypoglycaemia is of a variable standard and that this population is inadequately educated about the causes and management of hypoglycaemia (Brackenridge et al, 2006). The fact that these were the precise issues that were targeted by the DISNs may explain the improvements seen in the present study. 

The results also show that an unintended consequence of admission avoidance for these people may have been an increased risk of recurrent attendance to A&E, i.e. that admission avoidance may not have been the best course of action for a few people with diabetes who then would have re-presented and were then better managed with a short inpatient admission to deal with the consequences and causes of severe hypoglycaemia. 

The increased number of people with diabetes presenting to A&E with hypoglycaemia since 2004, with an accompanying reduction of mean HbA_1c level over the same period, is likely to be a reflection of improved glycaemic control across the local population with diabetes. This is probably a result of the incentivisation provided by the Quality and Outcomes Framework (QOF) in 2004 (Roland, 2004; Calvert et al, 2009), a system of performance-related pay for GPs. Payment is given for points gained according to the level of achievement against groups of set indicators, which in diabetes include recording the HbA_1c level, the proportion of people with an HbA_1c below 7.5% (58 mmol/mol), and the proportion of people with an HbA_1c level below 10% (86 mmol/mol) (NHS Employers, 2009).

In addition, the push towards more aggressive blood glucose lowering in people with diabetes has partly been driven by the publication of diabetes-related NICE guidance, which has provided national standards and targets for glycaemic control (NICE, 2002; 2009). 

The policy of encouraging the management of diabetes in the community rather than in hospital settings has meant that more insulin initiation occurs in primary care (Dale et al, 2010), potentially increasing the numbers of people with diabetes treated with insulin. The net result of all of these factors has been substantial increases in the number of blood glucose-lowering therapies (even accounting for the increased prevalence of diabetes) prescribed to people with diabetes over the years (Yorkshire and Humber Public Health Observatory, 2009).

Traditionally it was felt that hypoglycaemia was predominately a problem in people with type 1 diabetes (Pramming et al, 1991), and that the rates of hypoglycaemia in people with insulin-treated type 2 diabetes was much lower by comparison (Abraira et al, 1995). However, the present data would suggest that the numbers of people with type 2 diabetes attending A&E as a result of hypoglycaemia is only slightly less than those with type 1 diabetes. 

These results are broadly consistent with published research showing that hypoglycaemia requiring emergency assistance from healthcare professionals is almost as common in people with type 2 diabetes treated with insulin as it is in those with type 1 diabetes (Leese et al, 2003; UK Hypoglycaemia Study Group, 2009). In addition, a recent large-scale Diabetes UK survey revealed that half of the people with type 2 diabetes (excluding those treated with insulin) experienced at least one episode of hypoglycaemia during a fortnightly period (Diabetes UK, 2009). 

The main limitations of the present study are the potential inaccuracies in clinical coding in diabetes (Stone et al, 2010). Another potential source of error is the accuracy of the initial diagnosis of hypoglycaemia, as it can be seen from Table 2 that some people who are not taking any medication for diabetes had apparently attended A&E for hypoglycaemia, which seems improbable. However, these numbers are small and appear to be consistent year after year, and therefore should not have had a major influence on the overall results.

Conclusion
This study highlights the beneficial impact of improved liaison between DISNs and A&E, which resulted in reduced hospital admissions for hypoglycaemia. However, care needs to be taken to ensure that this approach does not increase multiple attendances.

These findings also highlight the need to individualise glycaemic control based on a person’s specific circumstances rather than taking a strict target-based approach. Both of these interventions have the potential to result in better health outcomes for people with diabetes by avoiding hypoglycaemia-related admissions and may therefore be cost-effective for PCTs.