Fig. 2

Item response probabilities Item Response Probabilities for identified disease clusters for the USA (a top left), Canada (b top right), England (c bottom left) and Ireland (d bottom right). Note: Definition of stroke includes transient ischemic attack; lung disease included a self-reported diagnosis or at least one of the following: emphysema, chronic bronchitis or chronic obstructive pulmonary disease; Psych1 was measured as self-reported diagnosis of any emotional, mental or psychological disorder; Psych2 included a self-reported diagnosis or at least one of: depression, anxiety disorder or bipolar disorder; Cancer excluded minor skin cancers and melanoma