Individuals with diabetes are at an increased risk of asthma. Insulin may further increase the risk of asthma, but the risk could possibly be reduced by using metformin.

Chronic obstructive pulmonary disease (COPD) is commonly staged according to the percentage of predicted forced expiratory volume in 1 s (FEV1 % pred), but other methods have been proposed. In this study we compared the performance of seven staging methods in predicting outcomes.We retrospectively studied 296 COPD outpatients. For each patient the disease severity was staged by separately applying the following methods: the criteria proposed by the Global Initiative for Chronic Obstructive Lung Disease (GOLD), quartiles of FEV1 % pred and z-score of FEV1, quartiles and specified cut-off points of the ratio of FEV1 over height squared ((FEV1·Ht−2)A and (FEV1·Ht−2)B, respectively), and quartiles of the ratio of FEV1 over height cubed (FEV1·Ht−3) and of FEV1 quotient (FEV1Q). We evaluated the performance of these methods in predicting the risks of severe acute exacerbation and all-cause mortality.Overall, staging based on the reference-independent FEV1Q performed best in predicting the risks of severe acute exacerbation (including frequent exacerbation) and mortality, followed by (FEV1·Ht−2)B. The performance of staging methods could also be influenced by the choice of cut-off values. Future work using large and ethnically diverse populations to refine and validate the cut-off values would enhance the prediction of outcomes.

The post-bronchodilator percent predicted FEV1 is better than the pre-bronchodilator percent predicted FEV₁ in the evaluation of the severity of disease in COPD patients and is more accurate in predicting the risk of death by the GOLD classification.

Background and objectiveA multidimensional assessment of COPD was recommended by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) in 2013 and revised in 2017. We examined the ability of the GOLD 2017 and the new 16 subgroup (1A–4D) classifications to predict clinical outcomes, including exacerbation and mortality, and compared them with the GOLD 2013 classifications.MethodsPatients with COPD were recruited from January 2006 to December 2017. The predictive abilities of grades 1–4 and groups A–D were examined through a logistic regression analysis with receiver operating curve estimations and area under the curve (AUC).ResultsA total of 553 subjects with COPD were analyzed. The mortality rate was 48.6% during a median follow-up period of 5.2 years. Both the GOLD 2017 and the 2013 group A–D classifications had good predictive ability for total and severe exacerbations, for which the AUCs were 0.79 vs 0.77 and 0.79 vs 0.78, respectively. The AUCs for the GOLD 2017 groups A–D, grades 1–4, and the GOLD 2013 group A–D classifications were 0.70, 0.66, and 0.70 for all-cause mortality and 0.73, 0.71, and 0.74 for respiratory cause mortality, respectively. Combining the spirometric staging with the grouping for the GOLD 2017 subgroups (1A–4D), the all-cause mortality rate for group B and D patients was significantly increased from subgroups 1B–4B (27.7%, 50.6%, 53.3%, and 69.2%, respectively) and groups 1D–4D (55.0%, 68.8%, 82.1%, and 90.5%, respectively). The AUCs of subgroups (1A–4D) were 0.73 and 0.77 for all-cause and respiratory mortality, respectively; the new classification was determined more accurate than the GOLD 2017 for predicting mortality (P<0.0001).ConclusionThe GOLD 2017 classification performed well by identifying individuals at risk of exacerbation, but its predictive ability for mortality was poor among COPD patients. Combining the spirometric staging with the grouping increased the predictive ability for all-cause and respiratory mortality.Summary at a glanceWe validate the ability of the GOLD 2017 and 16 subgroup (1A–4D) classifications to predict clinical outcome for COPD patients. The GOLD 2017 classification performed well by identifying individuals at risk of exacerbation, but its predictive ability for mortality was poor. The new 16 subgroup (1A–4D) classification combining the spirometric 1–4 staging and the A–D grouping increased the predictive ability for mortality and was better than the GOLD 2017 for predicting all-cause and respiratory mortality among COPD patients.

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