Proust had evidently come to use his illness as a pretext for escaping the ordinary contacts with the world, for being relieved from the obligations of punctuality and from embarrassing encounters. His super-normal sensitiveness must have made the social life which so fascinated him inordinately difficult for him; and his illness gave him a sort of counter-advantage over people whom, with the deep-rooted snobbery which co-existed with a bold and searching intelligence, he imagined to possess some advantage over him. His illness enabled him to come late and, by doing so, to attract attention; to attract attention and provoke compassion by sitting at dinner in his overcoat; or not to come at all and, by stimulating people's interest, to make them all the more eager to entertain him. (p. 167)In addition, here is a link to a 1927 article on Proust by Edmund Wilson in The New Republic.
Edmund Wilson was one of the most important literary critics of the 20th century. Axel's Castle is an essay collection covering Symbolist authors from Arthur Rimbaud to Gertrude Stein, and includes an excellent one on Marcel Proust. You can read the text here. Here is Wilson on Proust's multi-functional neurotic illnesses: