On the meaning of "sensitivity"

Area of Science:

• Analytical Chemistry
• Biochemistry
• Laboratory Medicine

Background:

• The definition of analytical method sensitivity is currently contested.
• Conflicting definitions by organizations like IUPAC (slope) and IFCC (detection limit) cause confusion.
• Misunderstanding the relationship between slope and detection limit leads to errors in method design, particularly in immunoassays.

Purpose of the Study:

• To address the controversy surrounding the definition of analytical sensitivity.
• To highlight the contradiction between the slope and detection limit definitions of sensitivity.
• To argue for the adoption of a single, unambiguous definition of sensitivity.

Main Methods:

• Review and critical analysis of existing definitions of analytical sensitivity.
• Examination of the implications of different definitions on method performance evaluation.
• Argumentation against the 'slope' definition based on common language usage and performance indication.

Main Results:

• Two primary definitions of sensitivity exist: response curve slope and detection limit.
• Investigators often incorrectly assume these definitions are inversely related.
• The 'slope' definition conflicts with the common meaning of sensitivity and is not a reliable performance indicator.

Conclusions:

• The ambiguity in defining analytical sensitivity must be resolved.
• The 'slope' definition is problematic and should be abandoned.
• Adopting a consistent definition is crucial for accurate method design and interpretation.