Eight illness groups were used for the validation of the IPQ-R. Seven of the samples
were collected in Auckland, New Zealand and an HIV patient group was recruited
from Brighton, United Kingdom. All patients had to read and write English and to
have a medical diagnosis of their condition to be included in the study. Three of the
patient groups, rheumatoid arthritis (RA), type II diabetes and asthma, were consecutively
recruited by a research assistant from Auckland hospital outpatient clinics as they
waited for their clinic appointments. Patient response rates were 90%, 92%, and 96%
respectively. The chronic pain patients (80% response rate) were recruited from hospital
based chronic pain clinics and the acute pain patients (50% response rate) from a
private physiotherapy practice. These patients were handed information about the
study during their treatment sessions. The chronic pain patients had all experienced
pain for longer than three months which was unexplained by medical signs alone.
The acute pain group presented with a first-time peripheral painful injury that had
been present for less than six weeks. The multiple sclerosis (MS) patients were recruited
from a mail out questionnaire survey to two Auckland-based MS support groups
(response rate 44%). The myocardial infarction (MI) sample consisted of consecutive
admissions to the Coronary Care Unit at Auckland Hospital with a confirmed diagnosis
of acute MI (response rate 96%). These patients completed the questionnaire within
one week of their MI while in the hospital. The HIV sample was recruited from a large
HIV/AIDS clinic in Brighton, United Kingdom. All eligible patients who attended
the clinic were invited to participate. Sixty percent of these returned the questionnaire.
The characteristics of the eight illness groups are presented in Table I.