The following patient information was recorded on the case report form by the attending physician to describe the patient's condition during the first visit: presence or absence of respiratory and other symptoms (cough, dyspnea at rest, pleuritic chest pain, acute confusion, acute deterioration of general condition, and/or acute aggravation of a coexisting chronic disease [eg, the impairment of glucose balance in diabetes or the deterioration of congestive heart failure]); duration of symptoms; date of examination; residential information (home, nursing home, municipal health center, or hospital ward); initial place of treatment (home, nursing home, municipal health center ward, or hospital ward); results of the initial physical examination (body temperature, respiratory rate, systolic and diastolic blood pressure, heart rate, and abnormal finding on chest auscultation, ie, rales); and whether the patient was in a terminal state. The patient data were complemented during the follow-up visit (or after death, if the patient died before the scheduled follow-up visit) with the basic laboratory data recorded at the initial visit: hemoglobin and C-reactive protein (CRP) levels; platelet and white blood cell (WBC) counts; erythrocyte sedimentation rate; concurrent illnesses or disabilities (eg, congestive heart failure, asthma, chronic obstructive pulmonary disease, dementia, chronic pyelonephritis, and/or type of diabetes); residence on a long-term ward; bedridden state; immunosuppressive treatment (ie, >5 mg/d of cytostatic medication or prednisolone); previous and current smoking habits; consumption of alcohol; information about possible travel abroad within the past month; final diagnosis; and, in fatal cases, whether the death was due to LRTI. To obtain valid and accurate information on the date of death and to confirm the registered coexisting illnesses, data concerning the study population were also drawn from the national register of the Finnish Social Insurance Institution, Kela. Information on dementia, dietary diabetes, alcohol abuse, and bedridden and terminal state was not available in the national register and was therefore obtained by a questionnaire. All data were stored in a computer database.