Population-bases Study to Asses Prevalence of Sleep Disorders and Their Association With Cardiovascular Risk Factors and Diseases

For the purposes of the present part of the Atahualpa Project, field personnel were trained to achieve expertise with the use of the screening questionnaires, and to assure uniformity in data collection. The independent review board of Hospital-Clínica Kennedy (Guayaquil, Ecuador) approved the study design and the informed consent form that has to be signed by all Atahualpa residents aged ≥40 years before enrollment in the study.

Field workers will perform a census of the population to detect all Atahualpa residents aged ≥40 years (including those who were not living at the village by the time of our previous census). Those "new" persons will be interviewed to assess their social and demographic characteristics and to evaluate their CVH status in the same way as it was done with the rest of the population in our most recent survey.

During the current survey, all consented persons will undergo a physical examination with attention to the measurement of the neck circumference, as well as the evaluation of facial characteristics relevant to the coexistence of sleep disorders, including retrognathia, nasal septum deviation, asymmetry of the nares, and palate position. The latter will be evaluated with the tongue resting inside the mouth (using the Friedman classification) and categorized into four classes according to which structures are visible: Grade I allows visualization of the entire uvula and tonsils/pillars, Grade II allows visualization of the uvula but not the tonsils/pillars, Grade III allows visualization of the soft palate but not the uvula, and Grade IV allows visualization of the hard palate only.

From the many questionnaires available for the detection of persons with suspected sleep disorders, our panel agreed to choose those that have been more widely used and have shown to be time-efficient, consistent and reliable for prediction of major sleep disorders. Field instruments include validated Spanish versions of the insomnia severity index, the Pittsburgh sleep quality index, the Epworth sleepiness scale, the Berlin questionnaire, and the four minimal diagnostic criteria for restless legs syndrome.

The insomnia severity index consists of seven questions evaluating nighttime sleep difficulties, sleep dissatisfaction, and impact of insomnia on the quality of life. Time-frame of such evaluation is in the two weeks before the test. Each question is rated on a five-point Likert scale ranging from 0 (not at all) to 4 (extremely) with a maximum total score of 28. Scores from 0 to 7 mean no clinically significant insomnia, 8 to 14 mean subthreshold insomnia, 15 to 21 mean moderate clinical insomnia, and 22 to 28 mean severe clinical insomnia.