Risk Factors Associated with Multiple Sclerosis: A Case-Control Study in Damascus, Syria

Table 1

Detailed inclusion criteria for each risk factor included in the study.

Smoking	This factor was considered upon the subject’s statement. Smoking cigarettes, shisha, or cigars was considered smoking, in addition to the subject being a chronic smoker (meaning that they had been smoking for a minimum of 5 months, and had developed dependence to tobacco). One-time smokers were not counted as smoking.
Family history of MS	This factor was considered upon the subject’s statement and their ability to recall.
Migraine	With no specific test to diagnose migraine, this factor was considered by revising the subjects’ folders in the medical archives, and each subject diagnosed with migraine by a neurologist working in the hospital or outside the hospital was considered for our study. Moreover, all subjects were asked to personally confirm our findings from their medical history.
Vitamin D deficiency	This factor was defined by a laboratory test of 25-hydroxy vitamin-D in blood, a level lower than 12 ng/ml indicated vitamin D deficiency.
Diabetes	Subjects suffering from chronic diabetes and taking medications on a daily basis to sustain their normal blood sugar levels were considered for this factor. In addition to the glucose fasting serum level test that was conducted to confirm our findings, pre-diabetes was only considered for this factor if the patient was taking medication to sustain normal sugar levels.
Hypertension	Each subject suffering from chronic hypertension and needing to take medication on a daily basis to sustain normal blood pressure was considered for this factor. Prehypertension (systolic 120-139/diastolic 80-89) was only considered if the patient was taking medications to sustain normal levels.
Appendectomy	We considered this factor upon the subject’s statement and with confirmation from the surgical history in the subject’s folders from the hospitals’ archives.
Tonsillectomy	We considered this factor upon the subject’s statement and with confirmation from the surgical history in the subject’s folders from the hospitals’ archives.
First-born child	We considered this factor upon the subject’s statements.