Relative strengths of preferences
| Study | Condition | Outcomes | Results, patients’ preferences only |
|---|---|---|---|
| Morss et al39 | Schizophrenia | 3 side effects: akathisia, tardive dyskinesia, parkinsonism | 33 patients with chronic schizophrenia gave their preferences for three side effects, using VAS scales, PC and SG. 78% of the patients had at least one of the side effects themselves. The SG disutilities for the three side effects reduced the expected quality of life by 12–16%. The expected mean value of life for akathisia and for tardive dyskinesia using the SG method was 0.88, while parkinsonism reduced the value to 0.84. Patients reported parkinsonism to be the worst side effect, using VAS and PC. The VAS method yielded significantly lower values than the SG method |
| Revicki et al48 | Schizophrenia | 5 health states: (1) inpatient, acute positive symptoms, (2) outpatient, negative symptoms, (3) outpatient, moderate function, (4) outpatient, good function, (5) outpatient, excellent function | 49 patients with schizophrenia used CRS and PC. The patients had relatively little psychopathology and cognitive impairment. Five hypothetical health states were presented to the patients. In the SG, patients valued being hospitalised and having acute positive symptoms the lowest (0.19), followed by the outpatient state with negative symptoms (0.30), and outpatient with moderate (0.49), good (0.57) and excellent (0.77) function. SG utilities in the current study were significantly higher than the CRS preferences for all health states |
| Lenert et al46 | Schizophrenia and schizoaffective disorder | 3 side effects: akathisia, tardive dyskinesia, parkinsonism | 22 patients with schizophrenia or schizoaffective disorder used VAS, PC and SG methods. The same three side effects as in Morss 1993 were presented to patients. The SG disutilities for each of the three side effects reduced the expected quality of life by 13–21%. The expected mean value of life using the SG method was 0.87 for akathisia and 0.88 for tardive dyskinesia, and 0.79 for parkinsonism. Parkinsonism was rated the worst side effect using the VAS scale. The VAS method yielded significantly lower values than the SG methods |
| Lee et al44 | Schizophrenia | 2 patterns of mental health impairment (less severe/more severe), based on 4 dimensions and 1 side effect: hostility/suspiciousness, anxiety/depression, withdrawal/retardation and thought disorder, and pseudo-parkinsonism | 20 patients with schizophrenia were included in the study, which used VAS and SG methods. Less and more severe health states based on four “dimensions” were presented to patients. Pseudoparkinsonism reduced the average SG values with 0.07, and using VAS: 0.08. The utilities of the four dimensions were not reported |
| Lenert and Kaplan28 | Schizophrenia | 6 health states with different degrees of symptoms (mild or moderate levels), with or without pseudo-parkinsonism, based on four symptom domains: thought disorders and disorders of cognition, withdrawal (negative symptoms), anxiety/depression and hostility | 148 patients with schizophrenia from geographically and clinically diverse environments gave their preferences for hypothetical health states representing four symptom domains similar to those in Lee et al, using VAS and SG methods. The reduction in utility between states without and with pseudo-parkinsonism was found to be approximately 0.07 (SG) and 0.14 (VAS) for milder states, and 0.05 (SG) and 0.07 (VAS) for more severe states (values based on figure in original article). Mild disease symptoms with pseudoparkinsonism was equally preferable to moderate symptoms without side effects. VAS scores were systematically higher than SG scores were. The utilities of the four symptom domains were not reported. |
| Shumway45 | Schizophrenia | 16 health states including 7 outcomes: positive symptoms, negative symptoms, extrapyramidal symptoms, tardive dyskinesia, social function, independent living, vocational function | 50 patients with schizophrenia in an outpatient setting rated 16 health states using rating scales and CA. Preference weights for seven outcome domains were computed using a CA procedure. The highest mean preference weight was found for social function (16.9), followed by, in descending order, positive symptoms (15.0), independent living and tardive dyskinesia (both 14.5), vocational function (14.1), extrapyramidal symptoms (13.5) and negative symptoms (11.5). There were no statistically significant differences between the ranked preferences |
| Briggs et al40 | Schizophrenia and schizoaffective disorder | 7 health states: stable disease, relapse and 5 side effects: weight gain, hyperprolactinaemia, diabetes, EPS and negative symptoms | 50 outpatients with schizophrenia or schizoaffective disorder rated health states directly on a preference assessment rating scale and then completed a TTO task for each health state. The highest mean utility was given to the stable schizophrenia state (0.92), followed by weight gain (0.83), hyperprolactinaemia (0.82), diabetes (0.77) and EPS (0.72). Relapse had the lowest mean utility (0.60) |
| Bridges et al36 | Schizophrenia | 20 treatment goals: decreased/increased depressive thoughts and feelings, cognition, satisfaction, performance, self-independence, physical health, psychotic symptoms, anxiety, social contacts, activities of daily living, capacity for work, self-confidence, family relationships, restlessness, visits to the doctor/hospital, improved communication, mistrust/hostility, irritability, capacity for emotion, sexual pleasure | 105 outpatients with schizophrenia ranked and rated 20 treatment goals in a self-explicated method study. The product of the ranking and rating (scale 0–100) revealed that decreased depressive thoughts and feelings was valued highest (58.5), followed by, in descending order, improved cognition (55.9), improved satisfaction (54.4), improved performance (52.6), improved self-independence (51.3), improved physical health (50.1), decreased psychotic symptoms (48.9), decreased anxiety (46.6), improved social contacts (45.3), improved activities of daily living (45.1), improved capacity for work (43.5), improved self-confidence (42.4), improved family relationships (38.9), decreased restlessness (36.9), decreased visits to the doctor/hospital (36.8), improved communication (35.9), decreased mistrust/hostility (31.9), decreased irritability (30.8), improved capacity for emotion (28.5) and improved sexual pleasure (24.2) |
| Kinter et al42 | Schizophrenia | 7 attributes, defined over 2 levels including: disease symptoms, relapse, clear thinking, social activities, extrapyramidal symptoms, daily activities, and support | 101 patients diagnosed with schizophrenia participated in this methodological study that compared two different CA designs. Seven patient-oriented attributes, each defined over two levels, were presented. The parameter estimate for the outcomes, using a D-efficient design, were in descending order, EPS (0.553), daily activities (0.522), support (0.451), social activities (0.364), clear thinking (0.332), relapse (0.196) and disease symptoms (0.107). All parameter estimates except disease symptoms were statistically significant within the model. Using the orthogonal design, EPS (0.756) and daily activities (0.623) also had the highest estimates, followed by clear thinking (0.454), support (0.446), social activities (0.313), and disease symptoms (0.269) and relapse (0.095). All parameter estimates except relapse were statistically significant within the model. The results of the two models were not statistically different |
| O'Brien et al38 | Mild or moderate depression | 7 side effects: blurred vision, tremor, sleepiness, dizziness, constipation, sweating, dry mouth | 95 patients with mild or moderate depression ranked and rated seven adverse effects. The maximum WTP per month (CAD) for a reduction in the incidence of each adverse effect was highest for blurred vision (21.9), followed by (in descending order) tremor (19.4), sleepiness (18.6), dizziness (16.8), constipation (15.8), sweating (13.9) and dry mouth (11.4). There was a statistically significant difference between the two extremes of blurred vision and dry mouth |
| Revicki 47 | Major depressive disorder | 11 health states, with varying depression severity, functioning and well-being, medication treatment, 8 side effects | Utilities for 11 hypothetical health states from 70 patients with major depressive disorder were obtained in this VAS and SG study. Severe, untreated depression had the lowest mean utility (0.30). 25% rated this state as worse or equivalent to death. The highest score was found for remission and no treatment (0.86), followed by depression in remission and maintenance treatment (0.72–0.83). The observed mean differences in utility for side effects compared to their absence ranged from 0.12 points for nervousness and light-headedness, to 0.01 points for dry mouth and nausea. Point values for sedation, headache, constipation and tension were not reported. The only side effect showing a statistically significant reduction in utility when present was light-headedness |
| Morey et al41 | Major depressive disorder | Different treatment characteristics presented in 40 states (20 choice pairs) varying the treatment characteristics of effectiveness, side effects (weight gain, little or no interest in sex, inability to achieve orgasm), money costs, hours of psychotherapy per month and use of antidepressants | 104 patients with major depressive disorder were included in the study. Using a willingness to pay (WTP) approach, treatment characteristics were varied in 20 different choice-pairs presented to patients. The monthly expected WTP was highest for “antidepressants with no side effects” and the combined treatment of “anti-depressants and 2 hrs therapy” (both $686 for a RI). WTP decreased if the antidepressant treatment had the side effect of no orgasm (WTP for an RI $478), weight-gain of 5% (WTP for an RI $409) or both these side effects (WTP for an RI $227) |
| Zimmermann et al35 | Depression | 18 hypothetical treatment outcome scenarios, differing in 8 attributes: depressed mood, loss of interest and enjoyment, loss of energy/fatigue, sleep disturbance, feelings of guilt, depression-related pain, treatment duration, side effects after 2 weeks | 227 patients with self-reported depression, currently or recently on antidepressants, used a choice-based conjoint analysis. 18 pairs of hypothetical treatment outcome scenarios differing on 8 attributes were presented. Loss of energy/fatigue was the most important outcome attribute (relative importance 18.5%), differing significantly from all other attribute importance values. The relative importance of side effects after 2 weeks was 14.2%, loss of interest and enjoyment 13.5%, depression-related pain 12.0%, sleep disturbance 12.0%, feelings of guilt 11.5% and duration of treatment 9.9%. Least importance was assigned to depressed mood: 8.5%. The factor levels most strongly affecting the utility scores for “loss of energy/fatigue” were “Can start and cope with all activities on his/her own” (utility score + 10.9) and “Cannot start or cope with any activities on his/her own” (-11.7). The factor level most strongly affecting the utility of “loss of interest and enjoyment” was “Has no interest in previous leisure activities” (-10.0). Standard deviations were given for factor levels but not for the attributes |
| Revicki et al43 | Bipolar disorder I | 55 health states differing in side effects, symptom severity, functioning, well-being and mono-/combination therapy | 96 patients in a VAS and SG study were presented hypothetical health states describing combinations of symptom severity, functioning, well-being and side effects. Mean utilities (0 anchored as death, 1 anchored as complete health) were calculated for inpatient states (0.12–0.33), inpatient mania states (0.23–0.26), severe depressive state (0.29), outpatient mania states (0.29–0.64), stable tardive dyskinesia (0.76) outpatient stable states with few clinical symptoms and no weight gain (0.58–0.83). A weight gain of more than 2.3 kg demonstrated an average 0.066 decrease in health state utilities. Patients preferred mono-therapy to combination therapies. The difference for weight gain was statistically significant. The difference in utilities for the outpatient and inpatient mania state was not statistically significant |
| Johnson et al34 | Bipolar disorder | 8 medication attributes including: frequency and severity of mania or depression episodes, side effects such as weight gain, cognitive deterioration, fatigue and the risk of developing an unspecified, but potentially life-threatening, side effect | 469 patients in a DCE gave their importance weights for eight medication attributes. Patients considered weight gain within 3 months to be most important (0.20), followed by cognitive impairment (0.185) and changes in the severity of depression (0.184). These outcomes were statistically significantly more important than a fatigue effect (0.11), mania severity (0.09), mania frequency (0.08), depression frequency (0.08) and risk of serious side effects (0.06). The values are approximate and based on the figures in the original article |
| Glenngård et al37 | ADHD | 5 health states: health state morning/workday (effectiveness), health state afternoon/early evening (effectiveness), side effects, dosing frequency per day, and price (cost of treatment per month) | 116 patients, all currently on ADHD, participated in DCE, presenting a combination of five hypothetical medication attributes, including attribute levels. Functioning in the morning and during school/workday was most important (WTP per month 252), followed by functioning during the afternoon/evening (WTP 145), number of dosages per day (WTP -43) and side effects (WTP -98) |
CA, conjoint analysis; CRS, categorical rating scale; DCE, discrete choice experiment; PC, pairwise comparison; RI, representative individual; SG, standard gamble; TTO, time trade-off; VAS, visual analogue scale; WTP, willingness to pay.