Instrument validation process: a case study using the Paediatric Pain Knowledge and Attitudes Questionnaire

To compare two methods of calculating interrater agreement while determining content validity of the Paediatric Pain Knowledge and Attitudes Questionnaire for use with Australian nurses.

Paediatric pain assessment and management documentation was found to be suboptimal revealing a need to assess paediatric nurses' knowledge and attitude to pain. The Paediatric Pain Knowledge and Attitudes Questionnaire was selected as it had been reported as valid and reliable in the United Kingdom with student nurses. The questionnaire required content validity determination prior to use in the Australian context.

A two phase process of expert review.

Ten paediatric nurses completed a relevancy rating of all 68 questionnaire items. In phase two, five pain experts reviewed the items of the questionnaire that scored an unacceptable item level content validity. Item and scale level content validity indices and intraclass correlation coefficients were calculated.

In phase one, 31 items received an item level content validity index <0·78 and the scale level content validity index average was 0·80 which were below levels required for acceptable validity. The intraclass correlation coefficient was 0·47. In phase two, 10 items were amended and four items deleted. The revised questionnaire provided a scale level content validity index average >0·90 and an intraclass correlation coefficient of 0·94 demonstrating excellent agreement between raters therefore acceptable content validity.

Equivalent outcomes were achieved using the content validity index and the intraclass correlation coefficient.

To assess content validity the content validity index has the advantage of providing an item level score and is a simple calculation. The intraclass correlation coefficient requires statistical knowledge, or support, and has the advantage of accounting for the possibility of chance agreement.