Publications

RATIONALE

Acute respiratory effects of low-level ozone exposure are not well defined in older adults.

OBJECTIVES

MOSES (The Multicenter Ozone Study in Older Subjects), although primarily focused on acute cardiovascular effects, provided an opportunity to assess respiratory responses to low concentrations of ozone in older healthy adults.

METHODS

We performed a randomized crossover, controlled exposure study of 87 healthy adults (59.9 ± 4.5 yr old; 60% female) to 0, 70, and 120 ppb ozone for 3 hours with intermittent exercise. Outcome measures included spirometry, sputum markers of airway inflammation, and plasma club cell protein-16 (CC16), a marker of airway epithelial injury. The effects of ozone exposure on these outcomes were evaluated with mixed-effect linear models. A P value less than 0.01 was chosen a priori to define statistical significance.

MEASUREMENTS AND MAIN RESULTS

The mean (95% confidence interval) FEV and FVC increased from preexposure values by 2.7% (2.0-3.4) and 2.1% (1.3-2.9), respectively, 15 minutes after exposure to filtered air (0 ppb). Exposure to ozone reduced these increases in a concentration-dependent manner. After 120-ppb exposure, FEV and FVC decreased by 1.7% (1.1-2.3) and 0.8% (0.3-1.3), respectively. A similar concentration-dependent pattern was still discernible 22 hours after exposure. At 4 hours after exposure, plasma CC16 increased from preexposure levels in an ozone concentration-dependent manner. Sputum neutrophils obtained 22 hours after exposure showed a marginally significant increase in a concentration-dependent manner (P = 0.012), but proinflammatory cytokines (IL-6, IL-8, and tumor necrosis factor-α) were not significantly affected.

CONCLUSIONS

Exposure to ozone at near ambient levels induced lung function effects, airway injury, and airway inflammation in older healthy adults. Clinical trial registered with www.clinicaltrials.gov (NCT01487005).

BACKGROUND AND AIMS

Balancing the risks for thromboembolism and postpolypectomy bleeding in patients requiring anticoagulation and antiplatelet agents is challenging. We investigated the incidence and risk factors for postpolypectomy bleeding on anticoagulation, including heparin bridge and other antithrombotic therapy.

METHODS

We performed a retrospective cohort and case control study at 2 tertiary-care medical centers from 2004 to 2012. Cases included male patients on antithrombotics with hematochezia after polypectomy. Nonbleeding controls were matched to cases 3 to 1 by antithrombotic type, study site, polypectomy technique, and year of procedure. Our outcomes were the incidence and risk factors for postpolypectomy bleeding.

RESULTS

There were 59 cases and 174 matched controls. Postpolypectomy bleeding occurred in 14.9% on bridge anticoagulation. This was significantly higher than the overall incidence of bleeding on antithrombotics at 1.19% (95% confidence interval, 0.91%-1.54%) (59/4923). We identified similarly low rates of bleeding in patients taking warfarin (0.66%), clopidogrel (0.84%), and aspirin (0.92%). Patients who bled tended to have larger polyps (13.9 vs 7.3 mm; P < .001) and more polyps ≥2 cm (41% vs 10%; P < .001). Bleeding risk was increased with restarting antithrombotics within 1 week postpolypectomy (odds ratio [OR] 4.50; P < .001), having polyps ≥2 cm (OR 5.94; P < .001), performing right-sided cautery (OR 2.61; P = .004), and having multiple large polyps (OR 2.92; P = .001). Among patients on warfarin, the presence of bridge anticoagulation was an independent risk factor for postpolypectomy bleeding (OR 12.27; P = .0001).

CONCLUSION

We conclude that bridge anticoagulation is associated with a high incidence of postpolypectomy bleeding and is an independent risk factor for hemorrhage compared with patients taking warfarin alone. A higher threshold to use bridge anticoagulation should be considered in patients with an elevated bleeding risk.

In a recent publication, Quintana-Dunque et al. studied patients with early onset rheumatoid arthritis (RA) and showed that baseline smoking status was inversely associated with disease activity and disability at 36 months. The authors conclude that smoking may not be as deleterious as previously considered in RA disease course. However, the authors fail to highlight several limitations of study design and analysis, including time-varying confounding, which may have a direct impact on results and corresponding conclusions.