Gezondheidsbewaking, medische triage en risicostratificatie

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1 1 Gezondheidsbewaking, medische triage en risicostratificatie Dick Heederik IRAS, Divisie Milieu-epidemiologie, epidemiologie, Universiteit Utrecht

2 Gezondheidsbewakingssysteem bakkerijbranche 2

3 Voorgeschiedenis ❼ Onderzoek naar allergie bij bakkers van Houba (1996) en meerdere vervolgsurveys: ❼ Sensibilisatie tarwemeel en enzymen>10-15% 15% van de werknemers ❼ Respiratoire klachten en BHR komen veelvuldig voor ❼ Advies van de Gezondheidsraad over mogelijkheden voor grenswaarde voor tarwemeelstof ❼ Voorstel grenswaarde commissie GBBS Gezondheidsraad 0,5 mg/m 3 8-uur tgg ❼ Voorstel advieswaarden allergenen GR

4 Grenswaarde, waarom gezondheidsbewaking ❼ Grenswaarde beperkt het risico op allergie, maar elimineert het niet volledig ❼ Gebaseerd op berekening van acceptabel risiconiveau (gezondheidsraad) 100 P(Sensitization) Heederik & Houba 2001 traditional bakers industrial bakers bakery supplies flour mill workers ,001 0,01 0, Wheat allergen exposure [µg EQ/m 3 ] 4

5 Dus een convenant Afspraken over voorlichting werkgevers en werknemers Stofbeheersingsplan en praktijkhandboek om stofarme werkwijzen te stimuleren Blootstellingsreductie voor industriele bakkers, meelfabrieken en de bakkerijgrondstoffen industrie (reductie piekblootstellingen met 50%) Evaluatie van maatregelen Gezondheidsbewaking onder blootgestelden 5

6 Surveillance ❼ Medical surveillance is the analysis of health information that may be occurring in the workplace and require targeted prevention. Surveillance can include both population- or group-based activities and individual activities. ❼ The individual-oriented activities are often referred to as worker screening and monitoring functions ❼ Aims: secondary prevention>early detection>subsequent management ❼ Questionnaires, serology/skin prick testing, (BHR) ❼ Protocols available for different industrial sectors (Platinum IPA; Laboratory Animal Workers) 6

7 Prediction research and surveillance ❼ Specific use of surveillance tools has not been described ❼ Detection or diagnosis of disease seldom on the basis of one test ❼ Prediction research a multivariate approach in design and analysis that accounts for mutual dependence between different test results. The information of every item can then be translated into a predicted probability of the chosen outcome. 7

8 Alternative approaches ❼ Triage or risk stratification: predict sensitization (ideally OA, OR) ❼ short questionnaire (scanned or internet based) and a diagnostic model for sensitization (phase I) ❼ referral to occupational health service or specialized clinic (phase II) ❼ results reported back to occupational health service for (exposure) intervention (phase III)

9 MODEL DEVELOPMENT (Editorial Suarthana Occup Env Med 2009 and J Clin Epid 2009) Available data 391 Dutch bakers (22.1% sensitised); Groningen study, 2002 Questionnaire items (>75) and detailed exposure data Logistic regression analyses with backward selection method Reference: IgE sensitization to wheat and or amylase allergens Model Performance Calibration: the Hosmer Lemeshow (H-L) goodness-of-fit test. Discrimination: area under the receiver operating characteristic curve (AUC) Model Validation Internal validation: bootstrapping procedure External validation: in new bakers Validation study

10 MODEL DEVELOPMENT Multivariate Association Asthma OR (95% CI) 2.7 (1.3 to 5.8) Rhinitis allergy 2.7 (1.6 to 4.6) Conjunctivitis allergy 1.6 (1.0 to 2.8) During work symptoms 2.0 (1.1 to 3.4) ❼Formula to calculate predicted probability of sensitization= 1 / (1 + EXP( - ( *asthma *rhinitis * conjunctivitis +.62 * during work symptom))).

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12 Diagnostic model as score chart Predictors Value Score Asthma symptoms Rhinitis symptoms Conjunctivitis symptoms During work allergic symptoms Sum scores Max 6.5 Sum score 0 1 Predicted probability (%)

13 Health Surveillance system ❼Phase I Questionnaires were distributed to and returned by bakers in the health surveillance program Probability of sensitization to wheat and/or amylase allergens was calculated for every baker using the diagnostic model Low probability group (sum scores 0-1) Medium probability group (sum scores ) High probability group (sum scores >= 3.5) ❼Phase II Will be enrolled in the next surveillance Refer to occupational health service Refer to clinic

14 Calibration and discrimination 50 1 % sensitivity > 30.0 Average predicted probability Observed proportion specificity Development set Referrence ❼(ROC) area 0.73 (95%CI 0.67 to 0.79) ❼False positives versus false negatives

15 Participation in Phase I Participation in Phase I bakers n= 5,348 Traditional bakery Employers n=1189 Workers n=3225 (60%) Industrial bakery Employers n=74 Workers n=1405 (80%) Flour milling Employers n=10 Workers n=398 (58 %) Baking products Employers n=13 Workers n=320 (58 %) Complete Questionnaire n=2686 (83%) Blood samples n=399 Complete Questionnaire n=1124 (80%) Blood samples n=214 Complete Questionnaire n=344 (86%) No blood samples Complete Questionnaire n=260 (81%) No blood samples ❼Validation study sample

16 Reasons for non-response* Afraid that their employee would use results against them No particular reason 0,03 0,06 The study was not important 0,1 Did not feel like to participate because did not have any symptoms Forgot to send back the questionnaire and or lost it Did not receive the questionnaire 0,29 0,33 0,33 0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 ❼N=86 bakers who did not returned short questionnaire, but participated in the validation study

17 Model Application

18 Model Application

19 Model Application

20 Results Phase III clinic (Meijer et al., ERJ 2010) ❼ Applied short (serology and BHR) and long diagnostic protocol ❼ 40% wheat, 14% α-amylase sensitized ❼ App. 50% of high scorers has BHR, a larger group has mild BHR ❼ 35% has work related asthma ❼ 20% work exacerbated asthma ❼ 15% work related allergic asthma ❼ Large proportion has severe work related rhinitis ❼ Misdiagnosis by GPs is a major issue (in app 30% work related cause is not suspected while being treated)

21 Intervention ❼ Intervention: ❼ Outplacement (Taskforce report ERJ and Eur Resp Review 2012) ❼ Exposure reduction in case of occupational allergy and occupational asthma? Vandenplas et al., Management of occupational asthma: cessation or reduction of exposure? A systematic review of available evidence. ERJ

22 Wetenschappelijke acceptatie van het gevolgde model? ❼ GR Advies. Preventie van werkgerelateerde luchtwegallergieën: advieswaarden en periodieke screening. Den Haag, ❼ Baur et al., for the ERS Taksforce. Guidelines for the management of work-related related asthma. ERJ 2012 ❼ Wilken et al., for the ERS Taskforce. What are the benefits of medical screening and surveillance? Eur Resp Rev

23 Praktische aspecten en vervolg ❼ Motivatie populatie vraagt outreaching benadering ❼ Communicatie tussen partijen en betrokkenen van groot belang ❼ Rol bedrijfsarts problematisch (doorverwijzing (expertise) en interventie (afwezigheid, of indien aanwezig positie en borging) ❼ Belang voor de werknemers is groot ❼ Prognose ❼ Ontbreken valide diagnose ❼ Ineffectieve behandeling huisarts ❼ Mogelijkheden van interventie ❼ Toekomst: diagnostische regels voor beroepsastma (reductie fout positieven en negatieven) 23

24 Ten slotte: Doorrekenen health impact (Warren et al., Occup Env Med 2009; Meijster et al., Occup Env Med 2010)

25 Doorrekenen health impact

26 Kosten baten analyse reguliere interventie versus gezondheidbewaking en interventie (Meijster et al., Occup Env Med 2011) ❼ Reguliere interventie leidde tot aan baten over 20 jaar voor een populatie van werknemers. Implementatie was kosten effectief voor alle belanghebbenden. ❼ Voor een gezondheidsbewakingssysteem, baten die resulteerden van een beperkte ziektelast werden geschat op