Objective To explore NHS staff members' perceptions and experiences of the contributory factors that may underpin patient safety issues in those who are placed on a hospital ward that would not normally treat their illness (such patients are often called ‘outliers’ ‘sleep outs’ or ‘boarders’).

Design Qualitative study using semi-structured interviews.

Setting A single large teaching hospital in the north of England.

Participants 29 members of NHS staff (doctors, nurses and non-clinical or management staff).

Results Five themes describing contributory factors underlying safety issues were identified: competing demands on staff time created by having patients on inappropriate wards and patients who are on the correct specialty ward to care for; poor communication between the correct specialty ward and the clinically inappropriate ward; lack of knowledge or specialist expertise on clinically inappropriate wards; an unsuitable ward environment for patients on inappropriate wards; and the characteristics of patients who are placed on clinically inappropriate wards (specifically staff perceive patients on inappropriate wards to be medically fit and therefore of lower priority and moving patients between wards may disorientate confused or impaired patients). Examples of how these contributory factors may lead to safety issues are given.

Conclusions NHS staff report that placement of patients on clinically inappropriate wards is a specific patient safety concern. The application of James Reason's Swiss cheese model of accident causation suggests that placement on an inappropriate ward constitutes a ‘latent condition’ which may expose patients to contributory factors that underlie adverse events.