Material and Methods:
A) sociodemographic variables:
Age, sex, marital status, occupation, pack\\year.
B) clinical variables:
1- Dyspnea measured by the Medical Research Council (MRC) scale and the COPD Assessment Test (CAT ) while stable, previous to admittance.
3- Charlson comorbidity index and age adjusted model.
4- The APACHE II scale: the severity of the episode upon admittance, calculated using the APACHE II scale, using the worst value obtained in the first 24h after being admitted to hospital.
5- the Sequential Organ Failure Assessment (SOFA) scale.
6- Lab parameters: such as glucose, albumin and heamatocrit
7- BAP-65 score: elevated blood urea nitrogen, altered mental status, pulse \> 109 beats/min, age \> 65 years.
8- Assessment of symptom of gastroesophageal reflux disease.
9-Glasgow scale score.
10-CURB 65 :"C" stands for "confused"; "U" stands for BUN greater than19 mg/dL; "R" stands for "respiration more than 30 breaths per minute""B" stands for blood pressure less than 90 mm Hg systolic or diastolic blood pressure 60 mm Hg or less; "65" stands ≥65 years.
11-CAUDA 70: C: Confusion, Acidosis (pH \<7.35), Urea \>7mmol/L, MRC Dyspnoea score \>4, Albumin \<35g/L, Age \>70 years. One point was assigned to each variable present, giving a six point scoring system.
12-The COPD and Asthma Physiology Score.
13-The early warning score.
14-ADO index: comprised of age, dyspnea by the MRC, and FEV1. Scores ranged from 0 (best status) to 5 (worst status) for age, 0-3 for MRC, and 0-2 for FEV1. Points for each component were added so that the ADO index ranged from 0 to 10.
