ALB and nutritional deficiency disease: Low body weight and serum albumin levels suggest a risk of malnutrition, which may lead to respiratory weakness and cough, decreased resistance, and susceptibility to infections that affect treatment outcomes.[29] In addition, elevated inflammatory markers and sputum clearance disorders are also predictive factors for noninvasive ventilation failure in COPD patients.[30] The inflammatory markers involved in this study mainly include white blood cell count, procalcitonin, and C-reactive protein.