Pendahuluan. Menegakkan diagnosis pneumonia pada pasien usia lanjut seringkali sulit mengingat gejala dan tanda klinis sering tidak lengkap dan manifestasi klinis yang tidak khas serta pemeriksaan penunjang yang sulit diinterpretasi. Hal ini mengkibatkan under ataupun over diagnosis dengan konsekuensi meningkatnya morbiditas dan mortalitas. Data faktor-faktor yang berhubungan dengan diagnosis pneumonia baik manifestasi khas ataupun tidak khas pada pasien usia lanjut belum banyak tersedia.Metode. Penelitian diagnostik dilakukan terhadap 158 pasien usia lanjut dengan kecurigaan pneumonia yang dirawat di Rumah Sakit dr. Cipto Mangunkusumo (RSCM) Jakarta pada kurun waktu Januari-Oktober 2010. Hubungan data klinis, laboratoris serta radiologis yang mencakup manifestasi spesifik (batuk, sputum produktif, sesak napas, demam, ronki, leukositosis , infiltrat) dan manifestasi tidak spesifik (intake sulit, jatuh, penurunan status fungsional inkontinensia urin) dengan diagnosis pneumonia komunitas dianalisis dengan regresi logistik. Kemudian, ditentukan kontribusi masing-masing determinan diagnosis terhadap diagnosis pneumonia. Kemampuan C-reactive protein dalam menegakkan diagnosis pneumonia dinilai dengan membuat kurva ROC dan menghitung AUC.Hasil. Dari 158 subjek, 106 didiagnosis pneumonia sesuai kriteria baku emas. Pada model akhir regresi logistik didapatkan tiga faktor yang berhubungan dengan diagnosis pneumonia yaitu batuk, ronki dan infiltrat dengan nilai p masing-masing secara berturut-turut yaitu <0,0001; 0,02; dan 0,0001. Nilai AUC yang diperoleh dari metode ROC untuk mengetahui kemampuan CRP dalam mendiagnosis pneumonia adalah 0,57 (IK 95%; 0,47-0,66).Simpulan. Faktor-faktor yang berhubungan dengan diagnosis pneumonia pada usia lanjut adalah batuk, ronki dan infiltrat. Sementara itu, c-reactive protein tidak memiliki peran dalam memprediksi diagnosis pneumonia pada pasien usia lanjut.Kata Kunci: diagnosis, pneumonia komunitas, usia lanjut Factors Related to Diagnosis of Community-Acquired Pneumonia in the ElderlyIntroduction. Diagnosing community-acquired pneumonia (CAP) in the elderly remains a clinical challenge for various reasons. The clinical manifestation in the elderly is not frank and atypical manifestations, e.g. falls, decrease of functional status and food intake or urinary incontinence, may be present. These reasons may be associated with under or over diagnosis, which consequently contribute to the higher observed mortality rate in the elderly population with CAP. Study about factors related to diagnosis of CAP in the elderly was ra rely performed. Methods. From January to October 2010, 158 elderly patients suspected of having pneumonia at RSCM were registered. Relationship between clinical, laboratory and radiologic factors which consist of classic manifestations (cough, productive cough, dyspnea, fever, rales, leucocytosis, infiltrates) and atypical manifestations (decrease of intake and functional status, falls, urinary incontinence) with diagnosis community acquired pneumonia were analyzed. Receiver operating characteristics analysis of C-reactive protein was performed to find its association with diagnosis of pneumonia.Results. Of 158 subject, 106 were confirmed of having pneumonia. Final model of multiple logistics regression analysis revealed three factors: cough (p<0,0001), rales (p=0,02) and infiltrate (p<0,0001) related to diagnosis of pneumonia. All four atypical manifestations were proved unrelated with diagnosis of pneumonia. The area under the ROC curve for c-reactive protein was 0,57 (95% CI 0,47- 0,66). Conclusions. Factors related with diagnosis of community-acquired penumoni in the elderly are cough, rhales and infiltrates. All four atypical manifestations are proven unrelated with diagnosis of pneumonia. C-reactive protein does not predict diagnosis of CAP in the eldery. Keywords: community-acquired pneumonia, diagnostic factors, elderly