4468
Thirty - five patients with primary pulmonary hypertension and 85 matched controls were recruited over 32 months ( 1992 - 1994 ) in Belgium .
 primary pulmonary hypertension
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 primary pulmonary hypertension