title: Risk of tuberculosis in patients with diabetes: population based cohort study using the UK Clinical Practice Research Datalink.
abstract: BACKGROUND
  Previous cohort studies demonstrate diabetes as a risk factor for tuberculosis (TB) disease. Public Health England has identified improved TB control as a priority area and has proposed a primary care-based screening program for latent TB. We investigated the association between diabetes and risk of tuberculosis in a UK General Practice cohort in order to identify potential high-risk groups appropriate for latent TB screening.
  
  
  METHODS
  Using data from the UK Clinical Practice Research Datalink we constructed a cohort of patients with incident diabetes. We included 222,731 patients with diabetes diagnosed from 1990-2013 and 1,218,616 controls without diabetes at index date who were matched for age, sex and general practice. The effect of diabetes was explored using a Poisson analysis adjusted for age, ethnicity, body mass index, socioeconomic status, alcohol intake and smoking. We explored the effects of age, diabetes duration and severity. The effects of diabetes on risk of incident TB were explored across strata of chronic disease care defined by cholesterol and blood pressure measurement and influenza vaccination rates.
  
  
  RESULTS
  During just under 7 million person-years of follow-up, 969 cases of TB were identified. The incidence of TB was higher amongst patients with diabetes compared with the unexposed group: 16.2 and 13.5 cases per 100,000 person-years, respectively. After adjustment for potential confounders the association between diabetes and TB remained (adjusted RR 1.30, 95 % CI 1.01 to 1.67, P = 0.04). There was no evidence that age, time since diagnosis and severity of diabetes affected the association between diabetes and TB. Diabetes patients with the lowest and highest rates of chronic disease management had a higher risk of TB (P <0.001 for all comparisons).
  
  
  CONCLUSIONS
  Diabetes as an independent risk factor is associated with only a modest overall increased risk of TB in our UK General Practice cohort and is unlikely to be sufficient cause to screen for latent TB. Across different consulting patterns, diabetes patients accessing the least amount of chronic disease care are at highest risk for TB.
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK. louise.pealing@lshtm.ac.uk.|TB Centre, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK. louise.pealing@lshtm.ac.uk.
authors.forename: Louise
authors.initials: L
authors.lastname: Pealing
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK. kevin.wing@lshtm.ac.uk.
authors.forename: Kevin
authors.initials: K
authors.lastname: Wing
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK. rohini.mathur@lshtm.ac.uk.
authors.forename: Rohini
authors.initials: R
authors.lastname: Mathur
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK. david.prieto@lshtm.ac.uk.
authors.forename: David
authors.initials: D
authors.lastname: Prieto-Merino
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK. liam.smeeth@lshtm.ac.uk.
authors.forename: Liam
authors.initials: L
authors.lastname: Smeeth
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK. david.moore@lshtm.ac.uk.|TB Centre, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK. david.moore@lshtm.ac.uk.
authors.forename: David A J
authors.initials: DA
authors.lastname: Moore
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D016208:Databases, Factual; D048909:Diabetes Complications / Q000453:epidemiology*; D003920:Diabetes Mellitus; D004739:England; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011320:Primary Health Care; D012307:Risk Factors; D014376:Tuberculosis / Q000150:complications / Q000453:epidemiology*; D055815:Young Adult