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DPPH Seminar: Possibilities of various study designs, Lammi Sept. 28-29, 09

DPPH Seminar: Possibilities of various study designs, Lammi Sept. 28-29, 09 Understanding occupational health intervention studies Jani Ruotsalainen, MSc, BSc, etc. So who the f@#k is this guy?!?. NOT associate Prof Jos Verbeek, sorry about that Researcher at FIOH and member of COHF

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DPPH Seminar: Possibilities of various study designs, Lammi Sept. 28-29, 09

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  1. DPPH Seminar: Possibilities of various study designs, Lammi Sept. 28-29, 09 Understanding occupational health intervention studies Jani Ruotsalainen, MSc, BSc, etc.

  2. So who the f@#k is this guy?!? • NOT associate Prof Jos Verbeek, sorry about that • Researcher at FIOH and member of COHF • Degrees from psychology and Ψ research methods • Published 4 Cochrane reviews in as many years • Currently working on 3 updates and a new protocol • Also in charge of the quality of COHF database of OH intervention studies (1412 records, Sep 27th) available through: www.cohf.fi This is why: • I know lots of stuff about intervention studies • my examples will come from occupational health Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  3. Timetable for this evening 15:00 – 16:00 Lecture 16:00 – 17:00 Group work 17:00 – 17:45 Dinner 17:45 – 18:45 Discussion 19:00 – Sauna, refreshments Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  4. Different kinds of medical research • Incidence/prevalence • Aetiological • Prognostic • Diagnostic accuracy • Intervention • Qualitative • Each answers a different kind of question • Needs its own quality criteria • Because of time constraints we concentrate on intervention research domain of the Cochrane Collaboration Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  5. Why do we need a separate database for OH intervention studies? • OH intervention studies are hard to find • Occupational health covers a vast range of medical fields • No specific indexing like MeSH terms in Medline • With an OH specialty database it is easier: • for researchers to conduct reviews and to find out what has not yet been studied • for OH professionals to refer to current best evidence • Classification helps in finding information: • about specific OH problems • a lot faster Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  6. What is an acceptable occupational health intervention study? PICO(S) • Participants: workers or employed patients • Intervention: purposely induced change • Comparison: e.g. usual care (placebo in drug trials) • Occupational health outcome(s) • exposure • behaviour • occupational disease, symptoms or signs • work ability, disability, return to work • injuries • quality of OHS • public health in the workplace • Study design: preferably RCT to minimize risk of bias Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  7. What is an (OH) intervention? • Any purposely induced change i.e. an active manipulation of the environment, disease or behaviour • Prima causa is either a researcher or • Some other instance (e.g. legislation) and a researcher is there to measure the effects • With the aim to improve occupational health or safety • What is the aim in improving nurse hand hygiene? What is NOT an intervention: • Correlation study (e.g. noise > hearing loss) • Other examples? Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  8. COHF codes for OH intervention studies Study designs (A1-A4) A1 Randomised Controlled Trial (RCT) A2 Controlled Before-After study (CBA) A3 Interrupted Time-Series (ITS) A4 Before-After study (BA) OH outcomes (B1-B7) B1 Exposure (to e.g. chemicals, noise, stress) B2 Behaviour  (e.g. wearing protective equipment) B3 Occ. disease and symptoms  (e.g. eczema, asthma) B4 Disability, sickness absence, return to work  B5 Injuries  B6 Quality of OH services  B7 Public health at the workplace  Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  9. Outcome measures • Ideally validated questionnaires, tests, etc. (MBI, HADS) • Sometimes what authors report as their result is NOT what they actually measured • E.g. better knowledge of safe work practices is NOT the same as using safer work methods • E.g. in a review about the effectiveness of stress interventions would you accept anxiety or depression measures as indicators of stress? Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  10. What is high quality? • Let's assume we have come up with 1) a nice intervention and 2) a bunch of valid outcome measures • What is the best way to estimate the "truth" regarding the effectiveness of our intervention? • In other words, what is a high quality intervention study? • What kind of evidence would you believe? • Exercise: • In twos or threes make up your own hierarchy of study designs starting from highest quality all the way to lowest quality • You have 5 minutes Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  11. Evidence hierarchy (one version) SUNY Downstate Medical Center. Medical Research Library of Brooklyn. Evidence Based Medicine Course. A Guide to Research Methods: The Evidence Pyramid. Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  12. Another version • Systematic literature review and meta-analysis of randomised controlled trials (RCT) • Narrative (unsystematic) review of RCTs • Single well performed RCT • Non-randomised, controlled trial • Time-series study • Uncontrolled before-after study • Case study (N = 1) • Expert opinion Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  13. Exercise: study design • Is a 4-hour stress management course effective in preventing stress in nurses compared to a booklet on stress management? • Compare pros and cons of different designs Design 1: • Course: 100 nurses in Helsinki University Hospital in 2009 • Book: 100 nurses in Turku Municipal Hospital in 2009 Design 2: • Kuopio University Hospital: 200 nurses randomly assigned to course or book in 2008 Design 3: • Course: 100 nurses in Oulu in 2008 • Book: 100 nurses in Tampere in 2004 Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  14. Randomised Controlled Trials Randomisation reduces systematic error or bias Randomisation Outcome + I Outcome − Outcome + C Outcome − • At participant level or at dept./company/worksite level • Idea is that chance "evens out" confounding factors (age, BMI, etc.) • Any difference between random allocation and selection? • More experimental control ≠ better research, only more accurate!!! Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  15. Controlled Before-After studies • Prospective, controlled studies, quasi-experimental Outcome + Allocation done according to convenience e.g. by wards Measured baseline similarity i.e. matching is NOT equal to randomisation Same goes for adjusting for confounders in analysis I Outcome − Outcome + C Outcome − Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  16. O+ O+ O− O− Injury count Time Interrupted time-series • At least three measurements before and after Intervention O+ O+ O+ O+ O− O− O− O− Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  17. Before-After Studies • Before-after assessment of programme evaluations or quality of care studies • Comparison with arbitrary or incomparable controls O+ O+ O− O− programme O+ O+ I¹ vs. I² O− O− Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

  18. Thank you for your attention! Understanding OH intervention studies / FIOH / Jani Ruotsalainen / 16.7.2014

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