When the households’ studied region and the order of their arrival were determined, invitations were received by telephone invitations. In every household, all of the individuals aged 35 to 70 year old which had the inclusion criteria without any exclusion criterion were studied.
 
The way of invitation of the eligible  households
Before starting to the invitation of the household, the total list of the eligible individuals was investigated by the prepared health houses and after the final approval, the invitation of the eligible  individuals was took place according to the following stages:
 

• The first stage was information about the study of Azar Cohort

• The invitation of the local trustees in order to make them familiar with the advantages and stages of the study

• Lecturing at public places such as mosques, cultural centers and schools

• Distribution of the public pamphlet of the introducing of the Azar Cohort study

• To install billboards at cities and villages

 
The second stage
In this stage the eligible individuals received invitation from phone call. The phone call was done 1 week before referring of the individuals. In this phone call the cases which individuals had to observe were explained such as do not short hands and feet nails, do not use color and henna for their hair, take shower one day before referring to the center, have identity card, identity document, a piece of photo, scissors, nail clipper and the used drugs, have a light meal for dinner and bring glasses. Besides, the day before presenting at cohort they phoned again individuals to recall them.