Medicinsk epidemiologi! Webbenkäter för datainsamling! För- och nackdelar! Olle Bälter! CSC, KTH!! 10.000-390.000 personer i studier!! Upp till 2000 frågor i en enkät!! Svarstider på flera timmar!! 80% ofullständigt ifyllda!! Kostnader på ca 500 SEK per enkät! Fördelar med webbenkäter!! Små marginalkostnader!! Omedelbar digital lagring!! Omedelbar kontroll av svar!! Individuell anpassning!! Logik minskar antalet frågor!! Minimal manuell hantering!! Mindre miljöpåverkan!! Nya typer av studier!! Omedelbar personlig återkoppling! Nackdelar med webbenkäter!! Ojämn fördelning av respondenter (ålder, ekonomi, utbildning)!! Jobbigare att läsa på skärm!! Kräver dator och datorkunskap!! Layout går inte att detaljkontrollera!! Högre initialkostnader!
Närmast sörjande! Billigt! Respondenturval! Fördelar! Nackdelar! Representativt?! För få! Anonymitet! Webbsidelänk! Billigt! För många! Internt i organisation! Panel! Slumpmässigt ur befolkningen! Billigt,! Många! Billigt,! Många! Många! Anonymitet! Uppbyggnad och underhåll! Initalkostnad! Datortyper! Fysisk Aktivitet och Nutrition Världens första (lyckade) generella webbdatainsamling!! Interaktivitet höjer svarsfrekvensen.!! Svarsfrekvens på andra delen av enkäten lika med papper.!! Framtida telefonkontakt med bibehållen svarsfrekvens.! Bakgrund!! Finns det ett samband mellan fysisk aktivitet, hunger, ätvanor, stress och fetma? (Ylva Trolle Lagerros & Elinor Fondells avhandlingar)!! Är Sverige moget för en slumpmässig webbstudie (2003)?! Studiedesign!! 900 slumpmässigt valda personer inbjudna.!! Tre grupper: papper, enkel webb och interaktiv webb.!! Uppföljning av alla respondenter. Hälften via telefon, hälften via papper.!! Två enkäter: 16 + 8 papperssidor,! 33 + 23 webbsidor (129 + 143 variabler).!
Kontakter!! Inbjudan via pappersbrev!! Pappersenkät eller URL med lösenord!! Påminnelse via papperspost!! Påminnelse via telefon!! Påminnelse via papperspost! Resultat!! Total svarsfrekvens:!! Papper 64% Webb 51%!! Telefonkontakt v.s. inte:!! Papper 55% v.s. 74%, Webb 51% v.s. 51%!! Andra enkäten:!! Papper 53%!! Enkel webb 58%!! Interaktiv webb 64%! Anledningar?!! Interaktivitet gör det roligare!! Vältestade instruktioner!! Iterativ utveckling!! Genomtänkt användarvänlig design!! Standardförfarande med påminnelser! Excellent compliance for multiple follow-ups using web questionnaires" Olle Bälter, School of Computer Science and Communication, KTH! Elinor Fondell & Katarina Bälter, Department of Medical Epidemiology and Biostatistics, Karolinska Institutet! Anna L.V. Johansson, Ylva Trolle Lagerros, Carl Johan Sundberg, Mats Lekander, Kenneth J. Rothman!
Can you do something about common cold?! How do you know someone has had a cold?! Physical Activity and Susceptibility to Upper Respiratory Tract Infection (URTI)! By far the most frequent disease in the industrialized world, being the number one reason for work absenteeism and presenteeism.! Previous studies have mostly focused on athletes or extreme groups of people.! No registers!! You have to ask while they remember! Participants were asked if they currently had an infection of the upper respiratory tract, or if they had had a new infection during the last three weeks, since we last asked.! Study population! Method! 5000 randomly selected men and women! Aged 20-59 years! Residing in a middle-sized county in northern Sweden! Web-based cohort study between January and May! Initial baseline web-based questionnaire including lifestyle factors, paper invitation! Web-based questionnaires distributed by email every third week during a 4-month-period! Participants were given feedback on their answers (BMI, energy expenditure, intake of fiber, calcium, iron and vitamin C). In addition they received information on how the entire group answered the previous questionnaire.!
LIME Study design! Contact/Reminders! Invitation to Baseline data!!end of! participate on exposures!!follow-up! January!Self-reported incidents!may!!! on infections! Initial questionnaire (paper mail)! Pre-letter!9 January! Password!23 January! Reminder!9 February! E-mail questionnaires, reminders 10 days later! 1 23 February! 2 15 March! 3 1 April! 4 26 April! 5 17 May! Results! 1805 completed the long baseline web questionnaire (36%)! After exclusions n=1509 were invited to the follow-up questionnaires.! Exclusions! Cold at baseline (N=244)! Lack of an e-mail address (N=17)! Did not want to give it to us (N=20)! Filtered our emails as junk mail (N=24)! 90 80 70 60 50 40 30 20 10 0 Compliance" 1st 2nd 3rd 4th 5th Nurses Health LIME
URTI frequency! Sample reflects the general Swedish population 25% 20% 15% 23% 23% 18% 17% 14% % URTI Identical! Prevalence of asthma (8%),! Smoking men (17%)! Overweight men (49.0% with BMI>25)! 10% 5% Slightly under represented! Smoking women (16% - 18%)! Overweight women (28-35% with BMI>25)! 0% 1st Follow-up 2nd Followup 3rd Follow-up 4th Follow-up 5th Follow-up Over represented! Education level >=2yrs 48% men 52% women 17% men, 20% women! Excercise helps! What is a METhour?! Highest group of physical activity (53-114 MET-hours per day) IRR of 0.7 (95% CI, 0.6-0.9)! MET = kcal / (kg body mass * h)! At rest # 21 METh/day! Couch potato # 27 METh/day! 1h excercise # 30 METh/day!
Conclusions! Physical Activity reduce risk of URTI! Web surveys can be used with excellent compliance with intense contact! Web surveys can facilitate new methods of data collection! For demos, see http://www.csc.kth.se/~balter/ webdemos.html!