Suicide lethality scale: Concerns regarding validity and scoring.

Sir,

Kar et al.[1] described the development of an instrument to measure the lethality of a suicide attempt. We have some concerns about the scoring of the instrument that they proposed, as well as about its face and content validity:

The minimum score on this scale is 5, not 0. There are known disadvantages of instruments that do not have 0 as the lowest rating; that is, the instruments that are not ratio scales[2]

The wording of many items requires improvement. For example, Item B could have been anchored as very high, high, moderate, low, and very low chances of rescue without requiring the grammatically awkward phrasing in the scale as it stands

The above notwithstanding, Item B does not measure lethality of the suicide attempt; it measures suicide intent

Item D is superfluous because there would be a 1 to 1 correspondence between the scoring of this item and the scoring of Item C. Item E is likewise superfluous because there is a 1 to 1 correspondence with Item A

Items C and D would be inapplicable, or scored at lower levels, if rescue occurred early. Because chance also plays a role in the rescue, the scoring of these items is contaminated by variables unrelated to lethality, and the lethality of an attempt could be underestimated.

Given these limitations, the instrument may require some revision before recommendation for use in research and practice.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.