Phosphodiesterase‐4 inhibitors leads to lower number of participants with 1 or more exacerbations compared with placebo (high certainty).
Phosphodiesterase‐4 inhibitors may leads to higher number of participants experiencing an adverse event compared with placebo (low certainty).
Phosphodiesterase‐4 inhibitors leads to higher gastrointestinal adverse effects: diarrhoea compared with placebo (high certainty).
Phosphodiesterase‐4 inhibitors probably leads to higher psychiatric adverse effects (roflumilast 500 µg) compared with placebo (moderate certainty).
Phosphodiesterase‐4 inhibitors showed no clear difference in mortality compared with placebo (moderate certainty).
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