- Questions 5 to 21 were referred to the last 12 months.

- For questions 9 to 14, four answers were offered:

• Never
• Sometimes (<25% of the times)
• Often (>25% of the times)
• Always

- For questions 16 to 18, four answers were offered:

• Never
• Fewer than once a week
• One o more times in a week
• Every day

Items included in the questionnaire mailed to subjects.

1. Indicate your age:
2. Indicate your gender:
3. Indicate your educational level:
4. Indicate your job:
5. Indicate the amount of fiber in your diet:  Low / Medium / High
6. How often do you perform physical exercise? Never / Sometimes / Habitually
7. Indicate which drugs are you taking:
8. Have you felt constipated? Yes / No
9. Do you strain during a bowel movement?
10. Do you feel an incomplete emptying sensation after a bowel movement?
11. How often are your stools hard?
12. Do you feel a blockage in the anus that makes it difficult to pass the stool?
13. Do you need to press around the anus or vagina to complete bowel movement?
14. Do you spend more than 10 minutes on the toilet to pass the stools?
15. How many bowel movements do you usually have each week?
16. Do you take oral laxatives?
17. Do you need to use suppositories to have bowel movements?
18. Do you need to use enemas to have bowel movements?
19. Have you visited a doctor because of constipation? Yes / No
20. Have you presented with abdominal pain more than 6 times last year? Yes / No  
21. Have you presented loose or watery stools? Yes / No