Guidelines for administering the questionnaire for psychotic experiences
This questionnaire has been developed to describe the characteristics and severity of hallucinations and delusions. The questionnaire can be administered to patients with different disorders and also to individuals without a diagnosis. Given the personal and at times even confronting nature of some questions, it is important to carefully introduce the interview. This can be done by explaining the purpose of the questionnaire and describing the kind of questions that can be expected. Try to make sure the participant feels at ease, and clearly indicate that breaks are possible during the interview. Be aware that psychotic experiences can be highly emotional experiences, possibly causing a luxation of symptoms. Indicate that the participant is always able to stop the interviewer when the symptoms worsen (e.g. voices become worse during course of the interview), and provide the participant with a feeling of control. When possible, discuss the effects of medication on concentration prior to scheduling the interview, and decide on the best time of the day to administer the questionnaire. It is important to explain that not all questions may apply to the participant and that parts of the questionnaire can therefore be omitted.
All items of the questionnaire apply to experiences over the past week. Only the frequency items (e.g. A1, V1, O1, O3 and O6) will be scored based on a broader timeframe, including the past week, the past month and lifetime. If the participant scores 2 or higher on these items (presence of the symptom over the past week), the remaining subscale items should also be queried.
During the interview, the questions printed in bold can be read out loud to the participant. The italicized items are optional and can be used (in no particular order) if further questioning is needed (indicated as ‘example questions’). The underlined items measure symptom severity and are quantitatively scored (answer options in numbers). If more than one answer applies for the severity items, the highest applicable answer should be scored. The other items describe symptom characteristics and are scored qualitatively (answer options in letters). If more than one answer applies to the descriptive items, all applicable answers can be scored (e.g. scoring multiple letters).
If an informant (e.g. relative, partner, nurse) is accompanying the participant during the interview, they can be invited to add information to the participant’s answer if necessary. We recommend interviewing the participant and informant at the same time, especially if the participant is cognitively impaired. However, as hallucinations and delusions are highly personal experiences, the answer of the participants takes priority if it deviates from the other informer.
The introductory item of the interview is intended to evaluate whether the participant is capable of understanding and answering the questions. If the participant scores 4 or 5 on this item, the reliability of the answers will be questionable. In that case, answers of informants may be of additional added value.
Guidelines for assessing the items on hallucinations and delusions
Scoring items on hallucinations
Hallucinations have perceptual qualities, e.g. they are heard, seen, tasted, smelled or felt. Do not incorporate ideas, (strange) thoughts or daydreaming when scoring hallucinations.
Scoring items on delusions
For each question, check whether a conviction or belief is indeed a delusion. This is the case when a conviction is almost certainly untrue, and not shared by others. Delusions are very salient for the participant. If the participant is not convinced of their conviction or belief, then it is not a delusion and most likely not even a delusional ideation (but may have been in the past). When assessing religious beliefs, ascertain these beliefs are consistent with recognised religions that are within the participant’s culture. Religious delusions are inconsistent with accepted spiritual beliefs.