The main finding of this study was that microvascular complications account for a substantial proportion of HCRU and costs in patients with diabetes and are, therefore, important economic and clinical targets. Crucially, enhanced diabetes care may be capable of preventing their occurrence [16, 17]. This study also showed that the economic impact of T2DM microvascular complications increases substantially with the severity of the complication. For example, treatment for patients with severe nephropathy accounted for more than a third of average inpatient costs per patient, largely driven by the cost of haemodialysis . Moreover, the average cost for patients with diabetic neuropathy, largely related to diabetic foot ulcer disease , was almost twice that of patients with nephropathy.
A previous study also assessed the economic impact of diabetic nephropathy in Germany ; while the study was much smaller in scale, the findings were consistent with this study, demonstrating higher costs with severe disease, largely driven by costs of dialysis. In the USA, costs have also been shown to rise substantially as nephropathy progresses . There is substantial evidence to show that intensive risk factor management and the early use of nephroprotective agents (e.g. ACE inhibitors, angiotensin receptor blockers) can prevent or delay progression of diabetic nephropathy, and that they are also cost-effective . Our findings confirm the additional burden on healthcare resources due to these complications, and they highlight the importance of identifying and managing these complications in the NHS, as efficiency becomes paramount in this finite system.
While it might be expected that patients with severe nephropathy would incur the highest proportion of inpatient stays in a nephrology department (86.7%), a similarly high proportion was observed in patients with both severe neuropathy (79.9%) and severe retinopathy (69.4%). Again, these data concur with other international reports regarding the burden of neuropathy . Although some of this increase could be due to coexistence of disease (e.g. renal and eye disease are widely recognised to occur together ), it also implies that any presentation with one microvascular complication in the outpatient or inpatient setting represents an opportunity to screen for, or assess, other, possibly more serious, microvascular complications. Presentation of neuropathy is varied and certainly during the early stages the methods of screening commonly used are highly subjective. Optimal methods of screening would therefore need to be determined and entered into economic models—for example, electrophysiological screening identifies more cases than questionnaire or scoring tools, but will be more costly .
Although the focus of this study is on microvascular complications, the presence of these complications is an indication of associated cardiovascular disease , such that risk profiling for macrovascular disease might be equally important in these settings. Our data showed that patients with T2DM use a variety of clinical services (i.e. not just endocrinology), many of which are associated with the management of complications (cardiology, nephrology, ophthalmology, general surgery, trauma and orthopaedics) that account for a significant share of all secondary care activity. It is to be expected that prevention of these complications would further reduce service demand in the inpatient setting but also implies that all such general areas should have access to specialist diabetic services that can assess and manage the patient globally. The proactive assessment of complications other than those that are the primary reason for attendance could be valuable in preventing later admissions.
There are some limitations in this study in that, as diagnosis is undertaken across multiple data sets (including retinopathy), it is likely that the database is more accurate in identifying local diabetes patients than non-local ones. In addition, as the date of first diagnosis is not currently available from primary care, and the date of first diabetes hospital usage is likely to be after diagnosis in many cases, using the date of first diabetes hospital usage as a de facto diagnosis date would likely underestimate the time since true diagnosis of population and may bias the results.
Finally, patients who only use retinopathy screening services (i.e. do not use HEFT core services) are excluded, as retinopathy is not a typical service provision of most major hospital trusts. Indeed, our data showed that, while there was a relatively stable incidence of nephropathy and neuropathy among patients with T2DM between 2010 and 2014, there was a significant decrease in the incidence of retinopathy (Fig. 5). This was possibly due to the high number of retinopathy screenings after the introduction of the Retinopathy Screening Service in 2008, and a subsequent decline in the background incidence rate due to improved disease management.
The variation in patient characteristics, HEFT service utilisation and economic resource usage between groups of patients with or without severe microvascular complications has been assessed for statistical significance using univariate statistical tests. These, therefore, do not control for possible confounding characteristics such as age or the presence of other comorbidities, which should be investigated in future work. Additionally, since this study encompasses the vast majority of HEFT patients with diabetes (subject to the limitations discussed above), the relatively large cohort ‘sample’ sizes (especially for retinopathy) tend to lead to formal statistical significance even when the absolute variation between groups may not be clinically relevant. Clinicians and health policymakers should assess the clinical meaningfulness of variations between groups when considering novel pathway interventions targeted at the patients considered in this study.