Measuring quality of life in patients with myocardial infarction or stroke: a feasibility study of four questionnaires in The Netherlands

Objective - To test in patients with a history of myocardial infarction or stroke the feasibility of four quality of life measurements - the Nottingham health profile (NHP), the heart patients psychological questionnaire (HPPQ), the sickness impact profile (SIP), and the hospital anxiety and depression scale (HAD). Design - Subjects were tested and retested after an interval of 14 days: questionnaires were self assessed. Subjects - Participants were randomly selected from the Rotterdam stroke data bank (stroke patients; n = 16, mean (SD) age 66-0 (11-0) years and from the population based Rotterdam study (myocardial infarction; n = 20, mean (SD) age 72-7 (7.9) years, controls; n= 17, mean (SD) age 72-8 (7.3) years. Measurements and main results - Mean (SD) administration times for the NHP, HPPQ, SIP, and HAD were 7'9 (3.5), 10-5 (4.3)

(J7 Epidemiol Community Health 1995;49:513-517) Measurement of disease outcome is an im- portant issue in medical research, especially in treatment trials.In general, this assessment can be applied at several levels of increasing complexity, as follows: (1) biological process, (2) impairments (of separate functions), (3) disability, (4) handicap (in which social roles are included), and (5) quality of life.'2Across the spectrum from disease process to quality of life, the measures become applicable to more than one disease.They usually also become less sensitive and less objective but closer to fulfilment of chosen roles and to well being, and therefore more relevant from the patient's point of view.3Quality of life has rarely been measured in controlled trials of patients with cardiovascular disease, although the importance of this measure is widely recognised.Sev- eral instruments for measuring quality of life have been developed, but their applicability to these specific groups of patients has hardly been tested.8  For our feasibility study we selected multi- dimensional instruments, for which there is wide experience of use.According to previous recommendations, the criteria used for the selection were concept, origin, format, content, scoring, validity, reliability, and responsiveness.9 0Two general purpose profiles designed for use in general populations were selectedthe Nottingham health profile (NHP) and the sickness impact profile (SIP)."-'4][17] We also selected a measure specific to heart disease that had been developed in The Neth- erlandsthe heart patients psychological questionnaire (HPPQ) -because of positive experience reported with this questionnaire in patients with heart disease in The Neth- erlands.'8`'9Since anxiety and depression are reported in both categories of patients and may influence their quality of life,2024 the hospital anxiety and depression scale (HAD), derived from clinical practice and with a reported practicality of use, was included as an indicator of the presence of anxiety and or depression.25-26   The primary objective of the present study was to test the selected instruments for their feasibility in two groups of patients -one with a history of stroke in the previous five years and the other with a history of myocardial infarction (MI) in the previous five years.We studied assessment time and test-retest reliability.In addition, we examined whether, in spite of the limited size of the study, NHP and SIP as general purpose profiles could dis- tinguish between patient groups and control groups.

Patients and methods
Since May 1990, all patients with a stroke or a transient ischaemic attack admitted to the University Hospital Rotterdam Dijkzigt have been registered in the Rotterdam stroke data bank, which was initiated by one of us (PJK).
From the data bank we randomly selected 16 patients who had had an ischaemic stroke more than six months before.One patient had experienced a transient ischaemic attack and the other 15 had had a brain infarct.The infarct was located in the right hemisphere in seven patients, in the left hemisphere in six patients, and in the posterior fossa in one patient: one patient had experienced multiple infarctions.
All patients were functionally independent and none suffered from aphasia.
From the Rotterdam study we selected 20 patients who had been admitted to hospital because of MI between six and 24 months previously.The Rotterdam study is a prospective follow up study which addresses de- terminants of the progression of chronic disabling disease in the population of 55 years and over in the district of Ommoord in Rotterdam.Altogether 7983 participants (78% of those invited) were recruited between 1991 and 1993.The Rotterdam study focuses on causally related determinants of major diseases in the elderly, especially conditions that interfere with the quality of life.There are four primary areas of research: cardiovascular diseases, neurogeriatric diseases, locomotor diseases, and ophthalmological diseases.After an initial home visit and interview, subjects are examined physically and have several clinical measurements made at a field centre.Some 2 5 years later, changes in health status and clinical measurements are reassessed.27  Seventeen controls, matched for age and gender from the MI patients, were selected from the Rotterdam study.Their medical history was negative for MI or stroke.The characteristics of the study groups are shown in table 1.

Results
Mean assessment time for the instruments in the different study groups varied between 5-2 minutes for HAD in the control group to 23-5 minutes for SIP in patients with a history of stroke (table 3).For the stoke patients the assessment time was longer for all instruments.
Median values for SIP total score, psy- chosocial and physical sum scores in the differ- ent study groups are presented in table 4, with corresponding p values.In tables 5, 6, and 7 the results are presented for different dimensions of NHP, HPPQ, and HAD.Most instruments were able to detect differences between the study groups.Statistically significant differ- ences were found for SIP (total score) in the comparison between MI patients and controls (table 4).For separate dimensions of SIP, stat- istically significant differences were found for emotional behaviour, for both post stroke patients and post MI patients in comparison with controls; for household management in Table 7 Hospital anxiety and distress (HAD) scores in the different study groups (median (interquartile range))   the comparison between post stroke patients and controls; and for mobility and recreation and pastimes between the post MI patients and controls.
For NHP there were statistically significant differences between both MI and stroke patients in the comparison with controls in the energy dimension and in part II, and in the pain dimension in the comparison between MI patients and controls (table 5).For the HPPQ differences in scores were statistically significant in both comparisons in all dimensions except for the social inhibition dimension (table 6).The anxiety scores of HAD were significantly different in both comparisons, and the depression score was significantly different between stroke patients and controls (table 7).
Test-retest reliability, calculated with Spearman correlation coefficients, is shown in table 8. Forty two subjects (79-2%) agreed to par- ticipate in this part of the study.Correlation ranged from 0 31 (p=0 05) in the SIP sleep dimension to 0-95 for HPPQ in the feelings of being disabled dimension (p<001).

Discussion
This preliminary study indicates that measures of quality of life can be applied within a reas- onable time to patients who have had MI or stroke and that these may distinguish even small numbers of patients from controls.Quality of life is an important aspect of health outcome, along with duration of life, and it is of interest as a determinant of outcome as well.32Inclusion of quality of life variables as measures of treat- ment effects is a valid and necessary addition to the more traditional outcomes considered in medical care, such as survival or the oc- currence of specific events.33When the choice is made to include the assessment of quality of life in a study of intervention or prognosis, one or several of the available instruments have to be selected, depending on a review of the literature and specific characteristics of the study.In general, the use of an existing in- strument is preferable to designing a new ques- tionnaire because several characteristics such as reliability and validity of existing instruments may be known, although of course for a specific study the addition of extra items can be neces- sary.
After careful selection, the next step is to test the feasibility and reliability of the selected instruments for the study population.The pres- ent study was designed to assess whether some of the instruments used would turn out to be less suitable than others and should be excluded from a planned main study with a larger number of participants.Use of all instruments was feas- ible in the study groups as judged from an acceptable administration time and from the subjects' reactions.Since the time elapsed since MI or stroke was at least six months, we ex- pected the condition of the patients to remain relatively stable and the correlations between assessments with an interval of 14 days to be high.Test-retest reliability was satisfactory.In spite of the relatively limited number of patients included, the instruments were able to detect differences between the study groups, some of them statistically significant.These results seem promising with regard to the sensitivity of the instruments.That the average age of the stroke patients was six years lower than that of controls may have contributed to the relatively low scores on SIP, but did not prevent the two HAD scores from being significantly higher than in controls.
The implications of some of the findings in the present study groups can be fully addressed only when based on a larger number of subjects.Given the performance of the instruments in the present study, however, we believe that they deserve to be considered by other investigators in similar research.

Table I
Charactenrstics of the study groups (mean (SD))

Table 4
Sickness impact profile (SIP): total score, psychosocial and physical sum scores in the different study groups (median (interquartile range))

Table 5
Nottingham heath profile (NHP) scores for different dimensions in the groups (medan (interquartile range))

Table 6
Heart patients psychological questionnaire scores in the different study groups (median (interquartile range))