Phone respondents reported less mental health problems whereas mail interviewee gave higher physical health ratings.
OBJECTIVE
This study examines the effects of telephone and mail interview methods on the measurement of health-related quality of life.


METHODS
One thousand six hundred ninety individuals aged 25-66 were interviewed randomly either by telephone or by mail. Health-related quality of life was assessed with the German SF-8.


RESULTS
Although respondents in the telephone survey were more willing to participate (77.4% vs. 47.5%) the difference in the accessibility of publicly available address and telephone records meant that overall more people were interviewed by mail than by telephone (53.2% vs. 46.8%). No differences occurred in terms of the sociodemographic makeup. Telephone respondents gave a more positive account of the mental dimension of their health-related quality of life; whereas mail interviews led to a better rating of the respondents' physical well-being. Gender-specific analyses indicate a slight discrepancy in the influence of the method of interviewing on men and women. Further differences were identified concerning the variance in the existence of ceiling and floor effects and the correlation between items.


CONCLUSIONS
Found differences are small but at least to be valued as relevant in certain settings. Therefore, we approve the use and development of factors of amendment.
Ravens-Sieberer
Ulrike
U
School of Public Health, WHO Collaborating Center, University of Bielefeld, Bielefeld, Germany. u.ravens-sieberer@uni-bielefeld.de
Erhart
Michael
M
Wetzel
Ralf
R
Krügel
André
A
Brambosch
Anett
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D004812:Epidemiologic Methods; D005192:Family Health; D005260:Female; D005858:Germany; D006304:Health Status; D006306:Health Surveys; D006801:Humans; D008297:Male; D008603:Mental Health; D008875:Middle Aged; D011177:Postal Service; D011788:Quality of Life; D012107:Research Design; D012737:Sex Factors; D013689:Telephone