Pulmonary Alveolar Proteinosis in Greece-Türkiye-Cyprus: Answers in a Real-Life Comparison

Pulmonary alveolar proteinosis (PAP) is a rare disease of inappropriate alveolar surfactant accumulation. The study objective was to compare Greece-Türkiye-Cyprus cohorts, followed-up for 20 years.

Data were retrieved retrospectively by chart review.

One hundred and thirty patients, Greece 39, Türkiye 87, Cyprus 4, were included; 115 (89%) autoimmune (a)PAP, 13 (10%) secondary, 1 (1%) hereditary. Abnormal anti-GM-CSF antibody titre was available in 86/115 patients, further analyzed for aPAP. Forty (46%) were male, with median (IQR) age at diagnosis of 40 (31-50) years. At median (IQR) duration of clinical follow-up of 39 (18-78) months, three patients died. Non-survivors had higher rates of cardiovascular disease [67% vs. 5%, p < 0.001], LTOT (67% vs. 13%, p = 0.001), pulmonary fibrosis [67% vs. 5%] and worse functional status at follow-up [FVC% pred 49 (29) vs. 87 (74-97); p = 0.026, DLCO% pred 21 (46) vs. 72 (58-82); p = 0.016]. aPAP patients were stratified by therapy group (no WLL-no i-GM-CSF, WLL alone, i-GMCSF alone and both WLL and iGM-CSF). WLL was more frequently performed in Türkiye and i-GMCSF alone in Greece (p = 0.006). All therapies were effective. No difference was detected on outcome when sole iGM-CSF was compared to WLL alone or in combination with iGM-CSF [deceased/alive 0%/100% vs. 7%/93%, p = 0.491]. Sole iGM-CSF significantly ameliorated clinical and functional parameters of disease severity [DLCO% (p = 0.013), SatO₂ (p = 0.002), 6MWT (p = 0.026)]. Across all therapy groups, pulmonary fibrosis eliminated beneficial response to treatment.

This first real-life comparison of aPAP cohorts originating from three countries showed the non-inferiority of sole iGM-CSF treatment. Fibrosis negatively affects response to treatment and survival.