Assessing the effectiveness of the COPD Assessment Test (CAT) to evaluate COPD severity and exacerbation rates.

AIMS: The CAT is a short, simple eight-item questionnaire for assessing and monitoring COPD. It is not known how reliable the CAT scores are for COPD patients who are frequently exacerbated. The effectiveness of the CAT for assessing COPD severity and exacerbation rates was evaluated. METHODS: This study enrolled 165 stable COPD patients who completed the CAT between April 2011 and February 2012. RESULTS: Patients had a mean forced expiratory volume in one second (FEV1) equal to 43.7% of the predicted value and a mean CAT score of 21.2 (± 7.56) units. There was a good association between the FEV1 (percentage of predicted value) and CAT scores (p < 0.0001). Frequent exacerbators had significantly higher CAT scores than infrequent exacerbators (24.8 ± 6.7 versus 17.5 ± 6.5, p < 0.0001). Also, as the frequency of the COPD exacerbations increased, CAT scores (p < 0.0001) significantly increased. There was a significant association between the frequency of hospitalization and the CAT scores (p = 0.001). CONCLUSIONS: We observed a good relation between the CAT, FEV 1, and disease severity in patients with COPD. We found that the baseline CAT scores are elevated in frequent exacerbators.

Nocturnal hypoxia and arterial lactate levels in sleep-related breathing disorders.

BACKGROUND: Lactate may be useful in pointing out the higher risk subgroups in sleep-related breathing disorders (SRBD) with various patterns of hypoxemia. We aimed to search whether morning and night lactate levels are related to apnea-hypopnea, hypoventilation, and hypoxemia in patients with SRBD and to compare it with patients without SRBD (No-SRBD). METHODS: Eighty patients with suspected SRBD underwent polysomnography (PSG) testing. SRBD patients had obstructive sleep apnea syndrome with or without sleep-related hypoventilation/hypoxemic conditions. Patients without SRBD were in the control group. Measurements included pulmonary function testing, PSG, analysis of arterial blood gases, and arterial lactate before and after PSG. Arterial lactate was compared with SRBD and No-SRBD patients. RESULTS: Morning lactate was significantly higher in the SRBD group than the No-SRBD group (1.65 +/- 0.48 and 1.35 +/- 0.57 mmol/L, respectively) (P = 0.003). Lactate levels at night and the change overnight in lactate levels were not significantly different between groups. After an adjustment for age, gender, and body mass index, lactate levels before PSG were related to the apnea-hypopnea index (beta: 0.004, 95% CI: 0.000-0.008) and the rate of sleep-time spent under 90% oxygen saturation (T90%). The following morning lactate level was correlated with the T90% (beta: 0.005, 95% CI: 0.000-0.010). After an adjustment for lactate levels before PSG, lactate in the morning was correlated with T90% (beta: 0.004, 95% CI: 0.000-0.008). CONCLUSION: As a marker of tissue hypoxia, arterial lactate may be used to assess the severity of SRBD.