Reinforcing breath carbon monoxide reductions in chronic obstructive pulmonary disease

Chronic Obstructive Pulmonary Disease (COPD) usually results from tobacco smoking. Smoking cessation slows COPD's progression, but few have studied anti-smoking treatments in COPD. In 3-month trials we paid lottery tickets during daily home visits to still-smoking COPD patients for reductions in breath carbon monoxide (CO), a measure of smoke intake. In our first protocol experimental patients received 0-3 tickets per day, depending upon the extent of CO reduction below pre-treatment baselines; yoked controls received the same number of tickets, but not contingent on CO. The protocol produced no change. In a second study patients were assigned a post-baseline quit-date, received nicotine gum, and were paid up to 5 tickets per night, but only for CO less than 10 parts per million (ppm). CO fell sharply as the intervention began, but gradually rose again. A third protocol added special reinforcement schedules for those who did not quit or relapsed (up to 20 tickets per night for CO less than 10 ppm). Daily CO concentrations fell from 27.1 parts per million (baseline mean) to 12.7 (intervention mean), but rapid increases followed the intervention. Few patients stopped smoking, but CO and cigarettes used per day significantly fell during Studies 2 and 3. Post-hoc analysis suggested only a small effect from gum.