Table 1. The questionnaire used in the study .

Questions	Possible answers
Age	... years
Gender	a) Male; b) Female
Level of education	a) Illiterate; b) Less than high school; c) High school graduate; d) College education
Occupational status	a) Unemployed; b) Worker/farmer; c) Government employee; d) Self-employed
What do you think CKD is?	a) An infection of the kidneys; b) Reduction in kidneys' ability to remove wastes from the blood; c) An inflammation of the kidneys; d) A stone of the kidneys; e) Do not know/no response
Which of the following symptoms/signs can manifest in early stages of CKD?	a) Pain in the flanks; b) Difficulty in urination; c) Change in smell/color of the urine; d) Urinating too little; e) Urinating too much; f) CKD can be asymptomatic until advanced stages; g) Do not know/no response
Choose two of the following diseases/conditions that you think are very likely to result in CKD.	a) Drinking too much water; b) Drinking low water; c) Smoking; d) Unmanaged diabetes; e) Unmanaged hypertension; f) Being male; g) Being female; h) Do not know/no response
Do you have diabetes? (As confirmed by a physician)	a) Yes; b) No
Do you have hypertension? (As confirmed by a physician)	a) Yes; b) No
If you have diabetes, has your doctor ever talked to you about your risk for developing CKD?	a) Yes; b) No
If you have hypertension, has your doctor ever talked to you about your risk for developing CKD?	a) Yes; b) No
How often do you counsel with your doctor/healthcare provider about your renal function?	a) Every 6 months; b) Every 12 months; c) Every 2 years; d) More than every 2 years; e) Do not know/remember
When was the last time that you have been tested for renal function?	a) Less than 6 months ago ; b) Between 6 and 12 months ago; c) Between 1 and 2 years ago; d) More than 2 years ago; e) Never been tested for renal function; f) Do not know/remember

The choices were presented in alphabetical order of Persian language to avoid giving precedence to any specific answer.