Relevant, biased or confounded results?

Relevant, biased or confounded results? Associations of environmental noise and respiratory symptoms in the National Childrens´ Respiratory Survey (OGYELF), Hungary, 2005 Mihály János Varró1, Zsolt Lang2, Anna Páldy1, Mária Bényi3, Gizella Nádor1, János Martin4, Gergely Tulipánt4, Anna Mácsik1, Eszter Szabó1, Péter Rudnai1 1National Institute of Environmental Health, Budapest, Hungary 2Nomogram Ltd., Budapest, Hungary 3National Center for Healthcare Audit and Improvement, Budapest, Hungary 4National Institute of Occupational Health, Budapest, Hungary

Former survey series: 1995–2002 • – Nat. Inst. Environ. Health (Budapest, Hungary): • 7–11 year old children (n~20,000) • – Standardized questionnaire • environmental health survey countrywide • (base: CESAR study; in more years: • anthropometric, spirometric etc. measures) • – Results: ISEE conferences also • – One of the questionnaire questions: • flat: near heavy traffic • (associations with health endpoints)

„Street with heavy traffic”; components: • – Physical: noise, vibration • – Chemical: air pollutants: NO2, CO, PM... • – Biological: polluted  modified pollen • (may become allergenic) • WHO Pan-European Housing & Health Study • – In 8 European town (in Budapest also) • – Noise: associations with many health endpoints • Noise • – Stress reaction; neuroimmune mechanisms

New questionnaire study: 2005 • – Primary schools in the whole country: • pupils in 3rd grade classes (>10 children/class) • – Postal delivery • (into 2726 schools, 100,333 questionnaires); • parental completion (voluntary); • sending back by: post/local medical officers

– Main question groups: • analogous to the former ones • (demographical data, perinatal factors, health endpoints, • parameters of the built environment, • lifestyle and social factors) • – Analogous and new questions; noise: • (1) Not disturbing [base] • (2) Slightly disturbing • (3) Disturbs sleep as well

Results • – From 2,160 schools(79.2%) • 62,711 questionnaires were sent back • (76.4% of the questionnaires • sent to the participating schools) • – Respiratory symptoms: • fast evaluation: • End of 2005; GIS • Asthmatic symptoms  • – Data entry (still in process; • now more than 40,000 questionnaires)

Methods of the 2nd phase • – Data entry:Epi Info v6.04d • – Analysis: STATA/W SE v9.2 • – Associations of noise and • respiratory (and allergic) symptoms

METHOD SUBJ. GOODNESS • – Logistic regression X • – Logistic regression XX • with robust variance estimation (one cluster variable) • – Logistic regression XXXX • with robust variance estimation (multistage) • ( same ORs; different SEs) • ( different ORs; different SEs) • – Random effects (+fixed effects) • logistic regression (one level) XXX • – Random effects (+fixed effects) • logistic regression (multilevel) X - - - - - - - - • (GLLAMM; user-written; extremely slow) • ( STATA 9) • ( STATA 10; R?! /www.r-project.org/) • – Mixed effects logistic regression XXXXXXXXX • (multilevel)

Multistage variance estimation • Sampling units (not in the capital): •  – Regions (NUTS-2) • – Counties (NUTS-3; not) •  – Small areas (NUTS-4) •  – Settlements • – Schools (not! • ~50% of the population: 1 school in 1 settlement) • Sampling units (capital – not now; too few data e.): •  – Districts • – City parts (not); postal codes (not) •  – Schools

Methods of the 2nd phase (contd.) • Adjustments: • – Gender, age (8 or 9 yrs) of the child; • – Ethnicity (Romany/not Romany) • – Settlement size (limits: ...5K...20K...50K…2M) • – Nearby traffic (clean air; light -, heavy traffic) • – Parents’ respiratory/allergic disease • – Chest disease (0–2 year) • – Psychosomatic symptoms (6 variables: • sleep disorders, tiredness, attention disorders, • irritability, anxiety, sadness)

Methods of the 2nd phase (contd.) • Adjustments (contd.): • – Factory inside of a 500 m radius • – Housing estate • – Crowdness (>1.5 person/room) • – Mould in the flat, any time • – ETS (>20 cig./day in the flat) • – Mothers’ education • (<8 elem. sch. classes; middle -, high school) • – Sport (only in the school; at home, too; officially) • – Television: >2 hrs/day • – Everyday’s living (hard/bad, middle, good/excellent) • – Social support

Preliminary results • – Data entry is in process • – The majority of Budapest data: later • – Multilevel mixed effect logistic models • are to be used later

Exclusions • All: 41,765 • Drops: • – For not living at the same place from birth, • – Different school/home postal code, • – Budapest & single sample units, • – More/less than 8–9 years old etc. • Altogether: -27,560 • ____________________________________________ • Left: 14,205

Demography: • – Boys: 49.1% • – Girls: 50.9% • – 8 yrs olds: 36.8% • – 9 yrs olds: 63.2% • – Romany: 6.7% • – Not Romany: 93.3% • By settlement size: • <5K: 38.1% • <20K: 31.7% • <50K: 15.6% • <1M: 14.6% • By traffic: • – Clean air: 17.3% • – Light traffic: 68.8% • – Heavy traffic: 13.9% • By noise: • – Not disturbing: 65.7% • – Slightly disturbing: 31.7% • – Disturbs sleep as well: 2.6%

Health outcomes • – Parents’ respiratory or allergic disease: 30.4% • – Chronic bronchitic symptoms: 16.3% • – Asthmatic symptoms (last 12 months): 10.2% • – Airway allergy: 16.0%

Stratifying • – Parents’ respiratory or • allergic disease, • – Traffic: • quite similar results

Hill’s criteria of causation and their application here Strength – The possibility of causation Consistency – Other investigations (–)Specificity – +/-  Temporal relationship – Necessary (Time series, Madrid, Spain; here: living at the same place…) Biological gradient – Dose-response relationship – Grades of exposition ?Biological plausibility and coherence – Knowledges… a new challenge? ?Experiment – On animals; on humans: ethics?! – Ex juvantibus (indirect)

Suggestions – Further analyses and investigations – (Data entry completing) – Personal noise measurements in a survey? – Clinical essays? – On-line noise monitors; spectral analysis? (Madrid, Spain) – Preventive measures – Favourable effect of harmonic music

Summary –Nat. Childrens´ Respir. Survey (OGYELF), Hungary, 2005 – Altogether ~63,000 questionnaires –Noise: 31.7%: slightly disturbing, 2.6%: disturbs sleep as well –Logistic regression models, with multistage variance estimation – Bronchitic, asthmatic and allergic symptoms: – aORs: 1.09**…1.28***, 1.47***…2.22*** – Personal noise measurements (survey); clinical essays – On-line noise monitors; spectral analysis – Preventive measures – Favourable effect of harmonic music

Summary Relevant, biased or confounded results? – Seems not to be biased – Seems not to be confounded – Seems to be relevant – ?

Thanks • Ministry of Health: financial background; • Office of the Chief Medical Officer, Leaders of the National Institute of Environmental Health (NIEH):support of the study; • The directors and teachers of the cooperating schools: the succesful process of the survey; • Parents: the correct fill-in of the questinnaires; • Territorial institutes of Nat. Publ. Health and Med. Officer Service: help in harvesting the questionnaires; • All co-workers of the Dept. of Environmental Epidemiology, NIEH:(Erzsébet Fleinek, Katalin Garancsy, Renáta Szentmihályi, Tamás Rudnai, Dr. Endre Sárkány, Györgyi Tóth): conscious and hard work

Thank you for your attention! E-mail: varro.mihaly@oki.antsz.hu

Relevant, biased or confounded results?