title: [A comparison of 2 survey methods: the telephone versus the mails in the diabetic population of a health center].
abstract: OBJECTIVE
  To find the differences between telephone and mail interview respect on answer rate, economic cost and characteristics of participants. To determine the knowledge of our diabetics about their disease.
  
  
  METHODS
  A descriptive transversal study.
  
  
  METHODS
  Primary care Centro de San Gregorio, Telde, Las Palmas.
  
  
  METHODS
  The diabetics type 1 and 2 (n = 566) of our centre, whose ages were 18-70 years. In order to apply the same health questionnaire through two different ways, we divided the sample into two random groups: mail group (n = 283) and telephone group (n = 283).
  
  
  RESULTS
  The global answer rate was 51.6% (292 patients), 48% in the mail group (136 patients) and 55% in the telephone group (156 patients). The total cost of the mail survey was 41,000 pts. (104 pts. per mail), and the cost of telephone survey was 5.100 pts. (25.5 pts. per useful call). In the whole sample, we observed women more frequently in the answer group (56% of 292) than in the no answer group (44% of 274) (CI 95% 8.1-12.8). Also, in the answer group, the age was greater than in the no answer group (58.8 +/- 9.8 yr vs. 55.8 +/- 12.5 yr) (CI 95% 1.14-4.8). When we analyzed gender and age in each group, we observed the same differences in the telephone group but not in the mail group. More than the half questionnaire were correctly answer by 64% (167 patients). In the telephone group the "fit" rate was greater (70.6% of 153) than in the mail group (55.7% of 106) (CI 95% 3.2-26.6).
  
  
  CONCLUSIONS
  A suitable answer rate was reached through both methods of interview, but telephone survey's was smaller. In the mail group, both genders and all ages groups answered in the same way. The knowledge of our diabetics about their disease was like as the found in another studies.
authors.affiliation: Centro de Salud de San Gregorio, Telde, Las Palmas.
authors.forename: M T
authors.initials: MT
authors.lastname: Martínez Ibáñez
authors.forename: E
authors.initials: E
authors.lastname: Hernández González
authors.forename: C D
authors.initials: CD
authors.lastname: Méndez García
authors.forename: J L
authors.initials: JL
authors.lastname: Gómez Juárez
authors.forename: J C
authors.initials: JC
authors.lastname: Salas Hospital
authors.forename: C
authors.initials: C
authors.lastname: Vázquez Veloso
authors.forename: R
authors.initials: R
authors.lastname: Solsona Gimeno
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016009:Chi-Square Distribution; D003151:Community Health Centers; D003365:Costs and Cost Analysis; D003625:Data Collection / Q000191:economics / Q000379:methods / Q000706:statistics & numerical data; D003922:Diabetes Mellitus, Type 1; D003924:Diabetes Mellitus, Type 2; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D007407:Interviews as Topic / Q000379:methods; D008297:Male; D008875:Middle Aged; D011177:Postal Service; D013030:Spain; D018709:Statistics, Nonparametric; D013689:Telephone