Eva Suarthana

Long-Term Outcomes in a Prospective Cohort of Apprentices Exposed to High-Molecular-Weight Agents

RATIONALE We conducted a long-term (8-yr) follow-up of 408 apprentices entering programs involving exposure to high-molecular-weight allergens. OBJECTIVES The objectives were to assess the frequency of new and persisting sensitization, symptoms, and bronchial hyperresponsiveness in relation with job history after ending apprenticeship and to examine characteristics significantly associated with the incidence and remission of these occupational outcomes. METHODS A respiratory symptom questionnaire, skin prick tests with work-related allergens (laboratory animals, flour, and latex), spirometry, and methacholine challenge were administered. The association between incidence or remission of these outcomes and individual characteristics at baseline and end of apprenticeship was examined. MEASUREMENTS AND MAIN RESULTS In subjects who at any time during follow-up held a job related to their training (78%), the incidence of sensitization, rhinoconjunctival and chest symptoms, and bronchial hyperresponsiveness at follow-up was 1.3, 1.7, 0.7, and 2.0 per 100 person-years, respectively. The remission of these outcomes acquired during apprenticeship was 18.5, 9.6, 9.6, and 12.4 per 100 person-years, respectively, in subjects no longer in a job related to training. Several clinical, immunological, and functional characteristics at baseline and acquired during apprenticeship were found to be significantly associated with the incidence and remission of the outcomes. CONCLUSIONS The incidence of sensitization, symptoms, and bronchial hyperresponsiveness was lower while at work than during the apprenticeship period. A high proportion of subjects in a job not related to training experienced remission of symptoms acquired during apprenticeship.

Wheat allergen exposure and the prevalence of work-related sensitization and allergy in bakery workers

Background:  Occupational airway diseases are common among bakers. The present study describes the association between exposure to wheat allergen levels and sensitization to wheat allergens, work‐related upper and lower respiratory symptoms and asthma in bakery workers.

A simple diagnostic model for ruling out pneumoconiosis among construction workers

Background: Construction workers exposed to silica-containing dust are at risk of developing silicosis even at low exposure levels. Health surveillance among these workers is commonly advised but the exact diagnostic work-up is not specified and therefore may result in unnecessary chest x ray investigations. Aim: To develop a simple diagnostic model to estimate the probability of an individual worker having pneumoconiosis from questionnaire and spirometry results, in order to accurately rule out workers without pneumoconiosis. Methods: The study was performed using cross-sectional data of 1291 Dutch natural stone and construction workers with potentially high quartz dust exposure. A multivariable logistic regression model was developed using chest x ray with ILO profusion category ⩾1/1 as the reference standard. The model’s calibration was evaluated with the Hosmer–Lemeshow test; the discriminative ability was determined by calculating the area under the receiver operating characteristic curve (ROC area). Internal validity of the final model was assessed by a bootstrapping procedure. For clinical application, the diagnostic model was transformed into an easy-to-use score chart. Results: Age 40 years or older, current smoker, high-exposure job, working 15 years or longer in the construction industry, “feeling unhealthy” and FEV1 were independent predictors in the diagnostic model. The model showed good calibration (a non-significant Hosmer–Lemeshow test) and discriminative ability (ROC area 0.81, 95% CI 0.74 to 0.85). Internal validity was reasonable; the optimism corrected ROC area was 0.76. By using a cut-off point with a high negative predictive value the occupational physician can efficiently detect a large proportion of workers with a low probability of having pneumoconiosis and exclude them from unnecessary x ray investigations. Conclusions: This diagnostic model is an efficient and effective instrument to rule out pneumoconiosis among construction workers. Its use in health surveillance among these workers can reduce the number of redundant x ray investigations.

Which tools best predict the incidence of work-related sensitisation and symptoms.

Background/aim: This study used information from the questionnaire alone or in conjunction with clinical tests, such as skin-prick testing (SPT) and bronchial responsiveness (BR) testing at entry, to develop models for estimating the probability of the occurrence of specific IgE-sensitisation to and respiratory symptoms in contact with laboratory animal (LA) allergens after 32 months’ training in an animal health technology programme. Methods: Four multivariable logistic regression models were developed for each endpoint, consisting of: (1) questionnaire; (2) questionnaire and SPT; (3) questionnaire and BR testing; and (4) questionnaire, SPT and BR testing. The prognostic models were derived from a cohort of Canadian animal health technology apprentices. The models’ internal validity and diagnostic accuracy were evaluated and compared. Results: Symptoms indicative of asthma and allergic symptoms at baseline composed the final questionnaire model for the occurrence of occupational sensitisation and symptoms. Both questionnaire models showed a good discrimination (area under the receiver operating characteristics curve were 0.73 and 0.78, respectively) and calibration (Hosmer-Lemeshow test p value >0.10). Addition of SPT and/or BR testing increased the specificity of the questionnaire model for LA sensitisation, but not for symptoms at work. To facilitate their application in practice, the final questionnaire models were converted to easy-to-use scoring system. Conclusions: Questionnaire is an easy tool that can give accurate prediction of the incidence of occupational sensitisation and symptoms.

A diagnostic model for the detection of sensitization to wheat allergens was developed and validated in bakery workers

OBJECTIVES To develop and validate a prediction model to detect sensitization to wheat allergens in bakery workers. STUDY DESIGN AND SETTING The prediction model was developed in 867 Dutch bakery workers (development set, prevalence of sensitization 13%) and included questionnaire items (candidate predictors). First, principal component analysis was used to reduce the number of candidate predictors. Then, multivariable logistic regression analysis was used to develop the model. Internal validation and extent of optimism was assessed with bootstrapping. External validation was studied in 390 independent Dutch bakery workers (validation set, prevalence of sensitization 20%). RESULTS The prediction model contained the predictors nasoconjunctival symptoms, asthma symptoms, shortness of breath and wheeze, work-related upper and lower respiratory symptoms, and traditional bakery. The model showed good discrimination with an area under the receiver operating characteristic (ROC) curve area of 0.76 (and 0.75 after internal validation). Application of the model in the validation set gave a reasonable discrimination (ROC area=0.69) and good calibration after a small adjustment of the model intercept. CONCLUSION A simple model with questionnaire items only can be used to stratify bakers according to their risk of sensitization to wheat allergens. Its use may increase the cost-effectiveness of (subsequent) medical surveillance.

Application of a prediction model for work-related sensitisation in bakery workers

Identification of work-related allergy, particularly work-related asthma, in a (nationwide) medical surveillance programme among bakery workers requires an effective and efficient strategy. Bakers at high risk of having work-related allergy were indentified by use of a questionnaire-based prediction model for work-related sensitisation. The questionnaire was applied among 5,325 participating bakers. Sequential diagnostic investigations were performed only in those with an elevated risk. Performance of the model was evaluated in 674 randomly selected bakers who participated in the medical surveillance programme and the validation study. Clinical investigations were evaluated in the first 73 bakers referred at high risk. Overall 90% of bakers at risk of having asthma could be identified. Individuals at low risk showed 0.3–3.8% work-related respiratory symptoms, medication use or absenteeism. Predicting flour sensitisation by a simple questionnaire and score chart seems more effective at detecting work-related allergy than serology testing followed by clinical investigation in all immunoglobulin E class II-positive individuals. This prediction based stratification procedure appeared effective in detecting work-related allergy among bakers and can accurately be used for periodic examination, especially in small enterprises where delivery of adequate care is difficult. This approach may contribute to cost reduction.

Risks for the development of outcomes related to occupational allergies: an application of the asthma-specific job exposure matrix compared with self-reports and investigator scores on job-training-related exposure

Background and aim: Risks for development of occupational sensitisation, bronchial hyper-responsiveness, rhinoconjunctival and chest symptoms at work associated with continued exposure to high molecular weight (HMW) allergens were estimated with three exposure assessment methods. Methods: A Cox regression analysis with adjustment for atopy and smoking habit was carried out in 408 apprentices in animal health technology, pastry making, and dental hygiene technology with an 8-year follow-up after training. The risk of continued exposure after training, estimated by the asthma-specific job exposure matrix (JEM), was compared with self-reports and investigator scores on job-training-related exposure. Associations between outcomes and work duration in job(s) related to training were also evaluated. Results: Exposure to animal-derived HMW allergens, subsequent to the apprenticeship period, as estimated by the JEM, was associated with a significantly increased risk for occupational sensitisation (hazard ratio (HR) 6.4; 95% CI 2.3 to 18.2) and rhinoconjunctival symptoms at work (HR 2.6; 95% CI 1.1 to 6.2). Exposure to low molecular weight (LMW) agents significantly increased the risk of developing bronchial hyper-responsiveness (HR 2.3; 95% CI 1.1 to 5.4). Exposure verification appeared to be important to optimise the sensitivity and the specificity, as well as HRs produced by the JEM. Self-reports and investigator scores also indicated that further exposure to HMW allergens increased the risk of developing occupational allergies. The agreement between self-reports, investigator scores, and the JEM were moderate to good. There was no significant association between respiratory outcomes and work duration in jobs related to training. Conclusion: The asthma-specific JEM could estimate the risk of various outcomes of occupational allergies associated with exposure to HMW and LMW allergens, but it is relatively labour intensive. Exposure verification is an important integrated step in the JEM that optimised the performance of the matrix.

Screening for occupational asthma by using a self-administered questionnaire in a clinical setting.

Objective: Because of its high prevalence, early screening for occupational asthma (OA) is crucial. We aimed to evaluate the screening performance of the Occupational Asthma Screening Questionnaire–11 items (OASQ-11) in a clinical setting. Methods: Between January 2009 and December 2011, 169 workers referred for potential OA to our hospital completed the OASQ-11 and underwent workups to determine the final diagnosis. The discriminative abilities of the OASQ-11 as a whole and in relation to demographic and exposure parameters were determined by the area under the receiving operator characteristic curve (AUC). Results: Model 1, consisting of the OASQs items, showed fair discrimination (AUC, 0.69; 95% confidence interval, 0.58 to 0.80). Addition of age and exposure duration to model 1 improved discrimination (AUC, 0.80; confidence interval, 0.72 to 0.88). Conclusion: A simple model consisting of the OASQ-11s items, age, and exposure duration could well discriminate subjects with OA in a clinical setting.

Repeated measures of placental growth factor, placental protein 13, and a disintegrin and metalloprotease 12 at first and second trimesters for preeclampsia screening.

OBJECTIVE To determine the utility of cross-trimester repeated measures of placental protein 13 (PP13), A disintegrin and metalloprotease 12 (ADAM12), and placental growth factor (PlGF) for preeclampsia (PE) screening. STUDY DESIGN A prospective cohort study of 893 nulliparous women who had serum sampling at 11 to 14 and 18 to 22 weeks. Biomarker levels were adjusted on maternal characteristics and gestational age. The accuracy and validity of maternal characteristics with single and repeated markers to predict PE were evaluated. RESULTS First-trimester PlGF was the best biomarker for PE (mean: 0.85 multiples of the expected median [MoM]) and early onset PE (0.79 MoM). First-trimester screening performances were not significantly improved by second-trimester markers. Area under the receiver operating characteristic curve was 0.73 (95% confidence interval [CI] 0.65 to 0.81) with first-trimester PlGF and 0.71 (95% CI 0.63 to 0.80) with first- and second-trimester PlGF (p = 0.301). CONCLUSION Repeated measures of PlGF, ADAM12, and PP13 at second trimester did not improve PE screening compared with first-trimester measures.

Predicting occupational diseases

Prediction research is relatively new in the occupational health field,1 2 3 4 although it is well established in clinical medicine.5 6 Prediction models are developed to estimate the individual probability of the presence (diagnostic model) or future occurrence (prognostic model) of an outcome (ie, disease). As an example from clinical practice, Wells and colleagues demonstrated that a diagnostic model (comprised of the patient’s history and physical examination) in combination with impedance plethysmography can safely rule out the presence of deep vein thrombosis. This approach reduced patient health care costs by avoiding expensive venography.5 Assessment of the 10-year risk of coronary heart disease (CHD) using the Framingham scores is a well known example of prognostic prediction.6 Such prediction allows physicians to identify a subset of patients with a higher probability of CHD in whom preventive action should be more effective. The development of prediction models makes it possible to identify a small number of predictors to provide the best possible knowledge base for diagnosis. These models enable risk groups to be easily identified by quantification of the individual probability of having an occupational disease. Recently, we …