Office visits to physicians.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010548:Personal Health Services / Q000706:statistics & numerical data*; D010820:Physicians; D012737:Sex Factors; D014481:United States