Publications by authors named "John D Norrie"
Robustly measuring multimorbidity using disparate linked datasets.
Commun Med (Lond)
July 2025
Background: Measurement of multimorbidity, the co-occurrence of two or more conditions in the same individual, is highly variable which limits the consistency and reproducibility of research.
Methods: Using data from 172,563 UK Biobank (UKB) participants and a cross-sectional approach, we examined how choice of data source affected estimated prevalence of 80 individual long-term conditions (LTCs) and multimorbidity. We developed code-list-based algorithms to determine the prevalence of 80 LTCs in (1) primary care records, (2) UKB baseline assessment, (3) hospital/cancer registry records, and (4) all three data sources together.
Background: Depression is associated with a range of adverse physical health outcomes. We aimed to quantify the association between depression and the subsequent rate of accrual of long-term physical health conditions in middle and older age.
Methods And Findings: We included 172,556 participants from the UK Biobank (UKB) cohort study, aged 40-71 years old at baseline assessment (2006-2010), who had linked primary care data available.
Risk-based, 6-monthly and 24-monthly dental check-ups for adults: the INTERVAL three-arm RCT.
Health Technol Assess
November 2020
Background: Traditionally, patients are encouraged to attend dental recall appointments at regular 6-month intervals, irrespective of their risk of developing dental disease. Stakeholders lack evidence of the relative effectiveness and cost-effectiveness of different recall strategies and the optimal recall interval for maintenance of oral health.
Objectives: To test effectiveness and assess the cost-benefit of different dental recall intervals over a 4-year period.
Background: Periodontal disease is preventable but remains the most common oral disease worldwide, with major health and economic implications. Stakeholders lack reliable evidence of the relative clinical effectiveness and cost-effectiveness of different types of oral hygiene advice (OHA) and the optimal frequency of periodontal instrumentation (PI).
Objectives: To test clinical effectiveness and assess the economic value of the following strategies: personalised OHA versus routine OHA, 12-monthly PI (scale and polish) compared with 6-monthly PI, and no PI compared with 6-monthly PI.
Background: Central to the design of a randomised controlled trial is the calculation of the number of participants needed. This is typically achieved by specifying a target difference and calculating the corresponding sample size, which provides reassurance that the trial will have the required statistical power (at the planned statistical significance level) to identify whether a difference of a particular magnitude exists. Beyond pure statistical or scientific concerns, it is ethically imperative that an appropriate number of participants should be recruited.
View Article and Find Full Text PDFBackground: Randomised controlled trials (RCTs) are widely accepted as the preferred study design for evaluating healthcare interventions. When the sample size is determined, a (target) difference is typically specified that the RCT is designed to detect. This provides reassurance that the study will be informative, i.
View Article and Find Full Text PDFBackground: The randomised controlled trial (RCT) is widely considered to be the gold standard study for comparing the effectiveness of health interventions. Central to the design and validity of a RCT is a calculation of the number of participants needed (the sample size). The value used to determine the sample size can be considered the 'target difference'.
View Article and Find Full Text PDFBackground: Central to the design of a randomised controlled trial (RCT) is a calculation of the number of participants needed. This is typically achieved by specifying a target difference, which enables the trial to identify a difference of a particular magnitude should one exist. Seven methods have been proposed for formally determining what the target difference should be.
View Article and Find Full Text PDFBackground: Periodontal disease is the most common oral disease affecting adults, and although it is largely preventable it remains the major cause of poor oral health worldwide. Accumulation of microbial dental plaque is the primary aetiological factor for both periodontal disease and caries. Effective self-care (tooth brushing and interdental aids) for plaque control and removal of risk factors such as calculus, which can only be removed by periodontal instrumentation (PI), are considered necessary to prevent and treat periodontal disease thereby maintaining periodontal health.
View Article and Find Full Text PDFArticle Synopsis
- Schizophrenia is linked to genetic factors and altered glutamatergic function, particularly in the prefrontal cortex, and a specific gene called MAP2K7 is supported as a potential contributor to the disease.
- In studies of post-mortem brain tissue, lower levels of MAP2K7 were found in individuals with schizophrenia, and mice with a single Map2k7 gene deletion displayed working memory issues similar to cognitive deficits seen in schizophrenia.
- Genetic association studies from Glasgow and Northern European populations indicated a significant relationship between a common variant of MAP2K7 and schizophrenia, suggesting that dysfunction of the MAP2K7 signaling pathway may play a role in the neurochemical changes associated with the disorder.
Object: The apolipoprotein E-epsilon4 (APOE-epsilon4) allele is associated with poor outcome after head injury and spontaneous intracerebral hemorrhage (SICH). The aims of this study were to determine if patients in whom one or more APOE-epsilon4 alleles are present are more likely to sustain intracranial mass lesions after head injury and to determine whether there is an isoform-specific effect on the size of the intracranial hematoma.
Methods: The authors performed a computerized volumetric analysis of 142 hematomas visible on computerized tomography (CT) scans obtained in 129 patients.