Higher Rates of Death and Major Bleeding Highlight the Inequities That Exist in the Care of People with Venous Thromboembolism Who Experience Social Exclusion: Findings from a Prospective Registry of 79735 Patients (RIETE)

Background

Social exclusion, experienced by vulnerable people at the margins of society, causes severe health inequity with dramatically increased risks of chronic disease and reductions in life-expectancy. Health services are not designed to meet the complex needs of socially excluded people (SEP).

SEP are frequently unintentionally excluded from large observational studies such as household surveys and surveys requiring active participation (Levitas et al, 2007). This lack of data deepens inequity.

Social exclusion in Ireland is strongly associated with injecting drug use, a strong risk factor for venous thromboembolism (VTE) (O'Reilly et al, 2015). Although an increased prevalence of VTE in lower socioeconomic groups has been described (Zoller et al, 2012), the impact of social exclusion and marginalisation on VTE has never been characterised in detail.

The Registro Informatizado de Enfermedad TromboEmbólica (RIETE Registry) is the world's largest database on patients with VTE. It was commenced in 2001 and continues to collect prospective data on consecutive patients presenting to hospital with acute VTE events. Patients are followed longitudinally, for a minimum of three months (Bikdeli et al, 2018).

One objective of the registry is to provide information on the natural history of VTE - particularly in subgroups of patients who would not usually be recruited to randomised clinical trials.

Methods

Our group has generated preliminary data (submitted separately to ASH 2019) which demonstrate that people with social exclusion can be identified from large national and international datasets using surrogate identifiers.

The RIETE registry already collects several of these data elements that can be used to identify people who are socially excluded: HIV infection (which is strongly associated with injecting drug use), liver disease, chronic alcoholism and chronic psychiatric illness.

We adapted the methodology developed in the Irish dataset and interrogated the RIETE registry utilising the available surrogate identifiers. We aimed to estimate the prevalence of social exclusion amongst patients with VTE, and to determine their clinical characteristics, treatment details and outcomes, with the ultimate goal of informing future service-planning and care-provision to this vulnerable group.

Results

At the time of interrogation of the RIETE registry, 79735 patients with VTE had been enrolled in 24 countries worldwide. Of these, 9211 (12%) met our criteria for SEP due to the presence of one or more of our surrogate identifiers. Of these, 60% presented with pulmonary embolism vs 52% in the non-SEP group (P<0.001), and SEP were more likely to have other medical co-morbidities.

Major bleeding was more frequent in the SEP group (5.36 vs 3.55 events per 100 patient-years; HR 1.51 (1.35-1.69)), particularly in those with liver disease (8.70 events per 100 patient years) or psychiatric disorders (5.31 per 100 patient years). Death occurred more frequently in the SEP group (17.9 vs 12.0 events per 100 patient years; HR 1.49 (1.40-1.58)), and recurrent VTE occurred most frequently in those with HIV infection (4.31 events per 100 patient-years) and liver disease (4.46 events per 100 patient years, compared with 3.46 in the non-SEP group).

Although Vitamin K Antagonists were used for longer term therapy in the majority of both patient groups (50% SEP, 63% non-SEP), the proportion who received low molecular weight heparin was higher in the SEP group (36% vs 26%). This was highest in the HIV infected subgroup, our identifier that best correlates with injecting drug use.

Conclusions

Social exclusion, as determined by the use of surrogate markers from a large prospective VTE registry, was associated with a higher overall incidence of death and major bleeding in patients treated for VTE.

These data highlight the inequities experienced by this vulnerable patient group, demonstrating the need for increased funding for service planning and care provision to better prevent and manage VTE. This can lead to reductions in hospital admissions and costs, but ultimately to the provision of equitable healthcare for SEP.