Unit Three: Epidemiology
Since this is a heterogeneous condition, the true epidemiological data is difficult to collect. Various research workers in different part of world have attempted to collect data according to their perception. There have been under diagnosis as well as over diagnosis.
The disease is usually found in adult females and the female to male ration is variously quoted as 9:1 to 5:1. The prevalence is between 4.5 /100,000 women in Japan to 20,000/100,000 women in USA. The global accepted prevalence is about 300/100,000 individuals. Almost 10-20 percent of all diagnosed cases are males.
There is no established evidence to prove that there is a genetic transmission of the disease, the familial clustering can be due to common social fabric including dietary practices.
Patients usually suffer for years together, sometimes more than 10 years before the diagnosis is made.
Let us now discuss the Clinical Features