Do statins affect risk of pneumonia in the general population: nested case control study

1. Do statins affect risk of pneumonia in the general population: nested case control study Yana Vinogradova Julia Hippisley-Cox Calgary 2007

2. Aims of presentation • Research study • Present analysis of study determining the risk of community acquired pneumonia in patients taking statins

3. Background to pneumonia statin analysis • Some evidence from lab data that statins benefit in case of infectious diseases • Statins can reduce rate of severe sepsis and ICU admission • Significant reduction in mortality • Reduction in fatal pneumonia risk • 51% reduction in diabetes patients

4. Study population: QRESEARCH database • Currently largest database in the UK • 537 UK practices • > 6 practices in every Strategic Health Authority (administrative area) • > 9 million patients including those who died, left and still registered • > 30 million person years of observation

5. Data source: QRESEARCH database • Patient level consolidated database • Anonymised data • Longitudinal data for 15+ years • Derived from GP clinical records • Validated against external and internal measures • Industry independent

6. Study design & setting • Nested case control study • Study period Jan 1996-Dec 2005 • Cases were incident community-acquired pneumonia patients • 5 controls matched by • Age • Sex • Practice • Calendar year

7. Assessment of exposure • analysis restricted to subjects with at least 2 years of prescribing data • use: at least 2 script in 12 months prior to the index date • different types of statins atorvastatin pravastatin cerivastatin simvastatin fluvastatin rosuvastatin • time for the last prescription: 28 days 29-89 days 90-365 days

8. Statistical analysis • Conditional logistic regression • Odds ratios + 95% CI • Unadjusted & adjusted

9. Socio-economic status Townsend quintiles Body mass index Less than 25 kg/m2 25 to 29.9 kg/m2 30 kg/m2 or more BMI not recorded Smoking status Non-smoker Smoker not recorded Morbidities List of comorbidites recommended for pneumococcal vaccination Additional comorbidities limiting mobility or suppressing immune system Vaccinations Influenza pneumococcal Confounding factors

10. Risk group for pneumococcal vaccine from current CMO guidance • Diabetes • Chronic heart disease • Chronic renal disease • Chronic respiratory disease • Asplenia • CSF Shunt • Chronic liver disease • Sickle cell or Coeliac disease • Cochlear Implant • HIV/AIDS • Immunosuppressed

11. New potential risk group • New conditions selected because • they limit the mobility • or can be associated with immunosuppression • Diseases included • Stroke or TIA • Rheumatoid arthritis • Parkinson’s disease • Common cancers • Multiple sclerosis • Dementia • Osteoporosis

12. Sample

17. Use of statin in the last 12 months • Adjusted for socio-economic status, body-mass index, smoking status, use of influenza and pneumococcal vaccinations and the co-morbidities

21. Main findings • any use of statin: • 13% to 23% decrease of pneumonia risk • use of statin within the last 28 days: • 22% to 32% decrease of risk

22. Methodological strengths • Large sample size and representative population • Data electronically collected – unlikely misclassification bias • Data collected before the diagnosis – no recall bias

23. Methodological weaknesses • Misclassification bias: no x-ray or microbiological confirmation • Misclassification of use: over-the-counter purchase • Data contain information on prescription, not actual use • Information on certain risk factors (alcohol intake) • Missing data for BMI, smoking

24. Conclusions • Recent use of statin is associated with reduced risk of community acquired pneumonia

25. Acknowledgements • QRESEARCH team • UoN • EMIS