title: Cross-sectional medicine -- a trap for the unwary.
mesh_terms: D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D004698:Endocarditis, Subacute Bacterial / Q000175:diagnosis; D004812:Epidemiologic Methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000175:diagnosis*; D009657:North Carolina; D013290:Streptococcal Infections / Q000175:diagnosis