Confounding by severity does not explain the association between fenoterol and asthma death

Area of Science:

• Respiratory Medicine
• Clinical Epidemiology
• Pharmacovigilance

Background:

• Case-control studies suggest fenoterol increases asthma mortality risk.
• The 'confounding by severity' hypothesis proposed preferential prescribing to severe asthmatics.

Purpose of the Study:

• To investigate the 'confounding by severity' hypothesis regarding fenoterol use in severe asthma.
• To analyze fenoterol prescription patterns in relation to asthma severity.

Main Methods:

• Analysis of data from New Zealand case-control studies on asthma deaths.
• Examination of fenoterol prescription patterns among hospitalized asthma patients.
• Subgroup analyses based on markers of asthma severity.

Main Results:

• Fenoterol was not preferentially prescribed to more severe asthmatics among those hospitalized.
• Co-prescribing patterns did not fully explain the excess risk associated with fenoterol.
• Inhaled fenoterol's relative risk increased with chronic asthma severity markers, contradicting confounding by severity.

Conclusions:

• The 'confounding by severity' hypothesis does not explain the increased asthma death risk associated with fenoterol.
• Findings suggest fenoterol itself may be linked to increased mortality in severe asthma.
• Further investigation into fenoterol's safety profile in asthma management is warranted.