Using a linked database for epidemiology across the primary and secondary care divide: acute kidney injury

Background

NHS England has mandated the use in hospital laboratories of an automated early warning algorithm to create a consistent method for the detection of acute kidney injury (AKI). It generates an ‘alert’ based on changes in serum creatinine level to notify attending clinicians of a possible incident case of the condition, and to provide an assessment of its severity. We aimed to explore the feasibility of secondary data analysis to reproduce the algorithm outside of the hospital laboratory, and to describe the epidemiology of AKI across primary and secondary care within a region.

Methods

Using the Hampshire Health Record Analytical database, a patient-anonymised database linking primary care, secondary care and hospital laboratory data, we applied the algorithm to one year (1st January-31st December 2014) of retrospective longitudinal data. We developed database queries to modularise the collection of data from various sectors of the local health system, recreate the functions of the algorithm and undertake data cleaning.

Results

Of a regional population of 642,337 patients, 176,113 (27.4%) had two or more serum creatinine test results available, with testing more common amongst older age groups. We identified 5361 (or 0.8%) with incident AKI indicated by the algorithm, generating a total of 13,845 individual AKI alerts. A cross-sectional assessment of each patient’s first alert found that more than two-thirds of cases originated in the community, of which nearly half did not lead to a hospital admission.

Conclusion

It is possible to reproduce the algorithm using linked primary care, secondary care and hospital laboratory data, although data completeness, data quality and technical issues must be overcome. Linked data is essential to follow the significant proportion of people with AKI who transition from primary to secondary care, and can be used to assess clinical outcomes and the impact of interventions across the health system. This study emphasises that the development of data systems bridging across different sectors of the health and social care system can provide benefits for researchers, clinicians, healthcare providers and commissioners.

Electronic supplementary material

The online version of this article (doi:10.1186/s12911-017-0503-8) contains supplementary material, which is available to authorized users.

Future projections of total hip and knee arthroplasty in the UK: results from the UK Clinical Practice Research Datalink

OBJECTIVE

To estimate the future rate of primary total hip (THR) or knee (TKR) replacement in the UK to 2035 allowing for changes in population demographics and obesity.

DESIGN

Using age/gender/body mass index (BMI)-specific incidence rates from a population-based cohort study of 50,000 THR and 45,609 TKR patients from the UK Clinical Practice Research Datalink (CPRD) between 1991 and 2010, we projected future numbers of THR and TKR using two models: a static, estimated rate from 2010 applied to population growth forecasts to 2035, and a log-linear rate extrapolation over the same period. Both scenarios used population forecast data from the UK Office for National Statistics (ONS).

RESULTS

Assuming rates of THR and TKR for 2010, and given projected population changes in age, gender and BMI, the number of THRs and TKRs performed in the UK in 2035 is estimated to be, respectively: 95,877 and 118,666. By comparison, an exponential extrapolation of historical rates using a log-linear model produces much higher estimates of THR and TKR counts in 2035 at 439,097 and 1,219,362 respectively. Projected counts were higher for women than men. Assuming a changing (rather than fixed) future BMI distribution increases TKRs by 2035 but not THRs.

CONCLUSIONS

Using historical rates and population forecasts we have projected the number of THR/TKR operations in the UK up to 2035. This study will inform policymakers requiring estimates of future demand for surgery. Incorporating future forecasts for BMI into projections of joint replacement may be more relevant for TKR rather than THR.

What is the risk of having a total hip or knee replacement for patients with lupus?

Individuals with systemic lupus erythematosus (SLE) frequently have arthralgia but joint damage leading to surgery is thought to be less common. In addition to inflammatory damage, other reasons like avascular necrosis (AVN), which is often associated with steroid use, excessive alcohol intake and antiphospholipid syndrome (APS), may increase the likelihood of large joint failure. In this study we aimed to determine the likelihood of having a total hip replacement (THR) or total knee replacement (TKR) for individuals with SLE compared to those without lupus, by performing a retrospective matched case control study of all THRs and TKRs that were performed between 1991 and 2011 and recorded in the General Practice Research Database (GPRD). Individuals with inflammatory arthritis due to any other causes were excluded and the results were adjusted for steroid use, alcohol consumption (drinking status) and APS. The results show that patients with lupus who had a THR or TKR were younger than their peers without lupus. In addition, they appeared to have a significantly increased risk of TKR but the increased risk of THR did not remain after adjustment for steroid use, alcohol consumption and APS.

Proinflammatory cytokines, sickness behavior, and Alzheimer disease

BACKGROUND

In Alzheimer disease (AD), systemic inflammation is known to give rise to a delirium. However, systemic inflammation also gives rise to other centrally mediated symptoms in the absence of a delirium, a concept known as sickness behavior. Systemic inflammation is characterized by the systemic production of the proinflammatory cytokines tumor necrosis factor-α (TNFα) and interleukin-6 (IL-6) that mediate immune to brain communication and the development of sickness behavior.

OBJECTIVE

To determine if raised serum TNFα or IL-6 are associated with the presence of sickness behavior symptoms, independent of the development of delirium, in a prospective cohort study of subjects with AD.

METHODS

A total of 300 subjects with mild to severe AD were cognitively assessed at baseline and a blood sample taken for inflammatory markers. Cognitive assessments, including assessments to detect the development of a delirium, and blood samples were repeated at 2, 4, and 6 months. The development of neuropsychiatric symptoms in the subject with AD over the 6-month follow-up period was assessed independently by carer interview at 2, 4, and 6 months.

RESULTS

Raised serum TNFα and IL-6, but not CRP, were associated with an approximately 2-fold increased frequency of neuropsychiatric symptoms characteristic of sickness behavior. These relationships are independent of the development of delirium.

CONCLUSIONS

Increased serum proinflammatory cytokines are associated with the presence of symptoms characteristic of sickness behavior, which are common neuropsychiatric features found in AD. This association was independent of the presence of delirium.

Systemic inflammation and disease progression in Alzheimer disease

BACKGROUND

Acute and chronic systemic inflammation are characterized by the systemic production of the proinflammatory cytokine tumor necrosis factor alpha (TNF-alpha) that plays a role in immune to brain communication. Previous preclinical research shows that acute systemic inflammation contributes to an exacerbation of neurodegeneration by activation of primed microglial cells.

OBJECTIVE

To determine whether acute episodes of systemic inflammation associated with increased TNF-alpha would be associated with long-term cognitive decline in a prospective cohort study of subjects with Alzheimer disease.

METHODS

Three hundred community-dwelling subjects with mild to severe Alzheimer disease were cognitively assessed, and a blood sample was taken for systemic inflammatory markers. Each subject's main caregiver was interviewed to assess the presence of incident systemic inflammatory events. Assessments of both patient and caregiver were repeated at 2, 4, and 6 months.

RESULTS

Acute systemic inflammatory events, found in around half of all subjects, were associated with an increase in the serum levels of proinflammatory cytokine TNF-alpha and a 2-fold increase in the rate of cognitive decline over a 6-month period. High baseline levels of TNF-alpha were associated with a 4-fold increase in the rate of cognitive decline. Subjects who had low levels of serum TNF-alpha throughout the study showed no cognitive decline over the 6-month period.

CONCLUSIONS

Both acute and chronic systemic inflammation, associated with increases in serum tumor necrosis factor alpha, is associated with an increase in cognitive decline in Alzheimer disease.

Midgut neuroendocrine tumours with liver metastases: results of the UKINETS study

We intended to identify the prognostic factors and the results of interventions on patients with liver metastatic midgut carcinoids. Five institutions that are part of United Kingdom and Ireland neuroendocrine tumour (NET) group took part in this study. Patients were included if they had histology proven NET of midgut origin and liver metastases at the time of the study. Clinical and biochemical data were collected retrospectively from hospital charts, pathology reports, radiology reports and biochemistry records for each patient. Three hundred and sixty patients were included in the study. The median survival from date of diagnosis was 7.69 years (confidence interval (CI) 6.40-8.99) and 5.95 years (CI 5.02-6.88) from date of diagnosis of liver metastases. On univariate analysis, increasing age at diagnosis, increasing urinary hydroxyindole acetic acid levels, increasing plasma chromogranin A levels, high Ki67, high tumour volume and treatment with chemotherapy were identified as factors associated with a significantly poorer outcome. Resection of liver metastases, resection of small bowel primary, treatment with somatostatin analogue therapy and treatment with peptide receptor therapy were associated with improved prognosis. Multivariate analysis revealed that age at diagnosis (P=0.014), Ki67 level (P=0.039) and resection of primary (P=0.015) were independent predictors of survival. This is the largest study to our knowledge looking specifically at the prognosis and clinical course of patients with liver metastatic midgut NETs. For the first time, we have shown that Ki67 and resection of primary are independent predictors of survival for this group of patients.