Effect of switching antipsychotics on antiparkinsonian medication use in schizophrenia: population-based study

Clinical consequences of switching from olanzapine to risperidone and vice versa in outpatients with schizophrenia: 36-month results from the Worldwide Schizophrenia Outpatients Health Outcomes (W-SOHO) study

BACKGROUND

With many atypical antipsychotics now available in the market, it has become a common clinical practice to switch between atypical agents as a means of achieving the best clinical outcomes. This study aimed to examine the impact of switching from olanzapine to risperidone and vice versa on clinical status and tolerability outcomes in outpatients with schizophrenia in a naturalistic setting.

METHODS

W-SOHO was a 3-year observational study that involved over 17,000 outpatients with schizophrenia from 37 countries worldwide. The present post hoc study focused on the subgroup of patients who started taking olanzapine at baseline and subsequently made the first switch to risperidone (n=162) and vice versa (n=136). Clinical status was assessed at the visit when the first switch was made (i.e. before switching) and after switching. Logistic regression models examined the impact of medication switch on tolerability outcomes, and linear regression models assessed the association between medication switch and change in the Clinical Global Impression-Schizophrenia (CGI-SCH) overall score or change in weight. In addition, Kaplan-Meier survival curves and Cox-proportional hazards models were used to analyze the time to medication switch as well as time to relapse (symptom worsening as assessed by the CGI-SCH scale or hospitalization).

RESULTS

48% and 39% of patients switching to olanzapine and risperidone, respectively, remained on the medication without further switches (p=0.019). Patients switching to olanzapine were significantly less likely to experience relapse (hazard ratio: 3.43, 95% CI: 1.43, 8.26), extrapyramidal symptoms (odds ratio [OR]: 4.02, 95% CI: 1.49, 10.89) and amenorrhea/galactorrhea (OR: 8.99, 95% CI: 2.30, 35.13). No significant difference in weight change was, however, found between the two groups. While the CGI-SCH overall score improved in both groups after switching, there was a significantly greater change in those who switched to olanzapine (difference of 0.29 points, p=0.013).

CONCLUSION

Our study showed that patients who switched from risperidone to olanzapine were likely to experience a more favorable treatment course than those who switched from olanzapine to risperidone. Given the nature of observational study design and small sample size, additional studies are warranted.

Construct validity of 2 measures to assess reasons for antipsychotic discontinuation and continuation from patients' and clinicians' perspectives in a clinical trial

BACKGROUND

Little is known about the specific reasons for antipsychotic discontinuation or continuation from patients' or clinicians' perspectives. This study aimed to assess the construct validity of 2 new measures of the Reasons for Antipsychotic Discontinuation/Continuation (RAD): RAD-I (a structured interview assessing the patient's perspective) and RAD-Q (a questionnaire assessing the clinician's perspective).

METHODS

Data were used from a 12-week antipsychotic trial of schizophrenia patients in which the RAD was administered at study entry and at study completion (or discontinuation). Construct validity was assessed through comparisons of RAD responses, clinicians' responses to a standard patient disposition form identifying reasons for patient's study discontinuation, and several standard psychiatric measures. Percent agreement quantified the correspondence between patient and clinician scores.

RESULTS

Patients indicating lack of improvement/worsening of positive symptoms as a 'somewhat' to 'primary' reason for medication discontinuation had statistically significantly less improvement in Positive and Negative Syndrome Scale positive score than patients not reporting these as a reason (concurrent validity). Similar results were observed for the RAD negative symptom, functional, social support, and adherence items, whereas the mood and cognitive items were not significantly associated with change scores on standard psychiatric measures. Responses to the RAD were also weakly associated with variables that theoretically should not be related to them (divergent validity). Level of agreement between the clinician- and patient-rated RAD scores was high (60%-100%).

CONCLUSIONS

Initial validation of the RAD suggests that the instruments are valid tools for gathering detailed information regarding reasons for antipsychotic discontinuation and continuation from patients' and clinicians' perspectives.

One-year outcomes in schizophrenia after switching from typical antipsychotics to olanzapine in Japan: an observational study

Background

The purpose of this study was to assess the 1-year clinical, functional, and safety-related outcomes following a switch to olanzapine of at least one typical antipsychotic drug in the previous regimen in the treatment of patients of schizophrenia in Japan.

Methods

Using data from a large 1-year prospective, multicenter, naturalistic study of olanzapine for the treatment of schizophrenia in Japan, patients who were switched from any oral typical antipsychotic to olanzapine were identified. Mixed models for repeated measures, controlling for baseline demographics, were utilized to assess outcomes for clinical and functional measures.

Results

Of the 262 patients who switched from typical antipsychotics to olanzapine, 41% were outpatients and 59% were inpatients. Most of these patients were switched due to poor medication efficacy (71.0%) or medication intolerability (25.6%). Most patients (71.4%) completed the 1-year study. Clinically and statistically significant (P < 0.01) improvements were observed in patient illness severity and health-related quality of life, including improvements in global symptom severity and in positive, negative, depressive, and cognitive symptoms. Over half of the patients (58.3%) demonstrated a treatment response to olanzapine and 47.4% achieved symptom remission. Mean weight gain from baseline to endpoint was 2.31 ± 4.72 kg, with 30.4% of patients experiencing clinically significant weight gain (at least 7% of baseline weight).

Conclusion

During this 1-year naturalistic treatment of schizophrenia patients in Japan, switching from typical antipsychotics to olanzapine resulted in significant improvements in patients’ clinical and functional outcomes. Approximately one-third of patients had clinically significant weight gain. These findings highlight the favorable benefit to risk profile of switching to olanzapine following failure on typical antipsychotics.

Improved outcomes following a switch to olanzapine treatment from risperidone treatment in a 1-year naturalistic study of schizophrenia patients in Japan

AIMS

This study assessed clinical and functional outcomes following a switch from risperidone to olanzapine in a 1-year naturalistic study of schizophrenia patients in Japan.

METHODS

We used data from a large 1-year prospective, multicenter, observational non-interventional study of individuals who were initiated on olanzapine for the treatment of schizophrenia in Japan. Current analyses focused on patients who were switched at study entry from risperidone to olanzapine (n = 258). Repeated measures analysis was employed to assess outcomes on validated measures.

RESULTS

At study entry, 45% were inpatients and 55% outpatients. Participants were in their early 40s with mean illness duration of 14 years. Approximately half were male. Most were switched from risperidone to olanzapine due to poor medication efficacy (67.8%) rather than medication intolerability (29.1%). Most patients (67.8%) completed the 1-year study. Patients experienced clinically and statistically significant (P < 0.05) improvements in global symptom severity, positive, negative, depressive, and cognitive symptoms, health-related quality of life, and paid work rates. Most patients (59.2%) demonstrated treatment response to olanzapine and 43.4% experienced symptom remission. Mean weight gain was 2.19 kg, with one-third of patients (33.3%) experiencing clinically significant weight gain (≥7%).

CONCLUSIONS

In this 1-year naturalistic study, inpatients and outpatients who were switched from risperidone to olanzapine experienced clinically and statistically significant improvements in their clinical and functional outcomes. One-third of all patients experienced clinically significant weight gain. Current findings highlight the favorable benefit-to-risk profile of switching to olanzapine therapy following treatment failure on risperidone among patients with schizophrenia in Japan.

Predictors of switching antipsychotic medications in the treatment of schizophrenia

BACKGROUND

To identify patient characteristics and early changes in patients' clinical status that best predict subsequent switching of antipsychotic agents in the long-term treatment of schizophrenia.

METHODS

This post-hoc analysis used data from a one-year randomized, open-label, multisite study of antipsychotics in the treatment of schizophrenia. The study protocol permitted switching of antipsychotics when clinically warranted after the first eight weeks. Baseline patient characteristics were assessed using standard psychiatric measures and reviews of medical records. The prediction model included baseline sociodemographics, comorbid psychiatric and non-psychiatric conditions, body weight, clinical and functional variables, as well as change scores on standard efficacy and tolerability measures during the first two weeks of treatment. Cox proportional hazards modeling was used to identify the best predictors of switching from the initially assigned antipsychotic medication.

RESULTS

About one-third of patients (29.5%, 191/648) switched antipsychotics before the end of the one-year study. There were six variables identified as the best predictors of switching: lack of antipsychotic use in the prior year, pre-existing depression, female gender, lack of substance use disorder, worsening of akathisia (as measured by the Barnes Akathisia Scale), and worsening of symptoms of depression/anxiety (subscale score on the Positive and Negative Syndrome Scale) during the first two weeks of antipsychotic therapy.

CONCLUSIONS

Switching antipsychotics appears to be prevalent in the naturalistic treatment of schizophrenia and can be predicted by a small and distinct set of variables. Interestingly, worsening of anxiety and depressive symptoms and of akathisia following two weeks of treatment were among the more robust predictors of subsequent switching of antipsychotics.

Efficacy of atypical v. typical antipsychotics in the treatment of early psychosis: meta-analysis

BACKGROUND

There is an ongoing debate about the use of atypical antipsychotics as a first-line treatment for first-episode psychosis.

AIMS

To examine the evidence base for this recommendation.

METHOD

Meta-analyses of randomised controlled trials in the early phase of psychosis, looking at long-term discontinuation rates, short-term symptom changes, weight gain and extrapyramidal side-effects. Trials were identified using a combination of electronic (Cochrane Central, EMBASE, MEDLINE and PsycINFO) and manual searches.

RESULTS

Fifteen randomised controlled trials with a total of 2522 participants were included. No significant differences between atypical and typical drugs were found for discontinuation rates (odds ratio (OR) = 0.7, 95% CI 0.4 to 1.2) or effect on symptoms (standardised mean difference (SMD) = -0.1, 95% CI -0.2 to 0.02). Participants on atypical antipsychotics gained 2.1 kg (95% CI 0.1 to 4.1) more weight than those on typicals, whereas those on typicals experienced more extrapyramidal side-effects (SMD = -0.4, 95% CI -0.5 to -0.2).

CONCLUSIONS

There was no evidence for differences in efficacy between atypical and typical antipsychotics, but there was a clear difference in the side-effect profile.

The 2009 schizophrenia PORT psychopharmacological treatment recommendations and summary statements

In light of the large number of studies published since the 2004 update of Schizophrenia Patient Outcomes Research Team psychopharmacological treatment recommendations, we conducted an extensive literature review to determine whether the current psychopharmacological treatment recommendations required revision and whether there was sufficient evidence to warrant new treatment recommendations for prespecified outcomes of interest. We reviewed over 400 articles, which resulted in 16 treatment recommendations: the revision of 11 previous treatment recommendations and 5 new treatment recommendations. Three previous treatment recommendations were eliminated. There were 13 interventions and/or outcomes for which there was insufficient evidence for a treatment recommendation, and a statement was written to summarize the current level of evidence and identify important gaps in our knowledge that need to be addressed. In general, there was considerable consensus among the Psychopharmacology Evidence Review Group and the expert consultants. Two major areas of contention concerned whether there was sufficient evidence to recommend specific dosage ranges for the acute and maintenance treatment of first-episode and multi-episode schizophrenia and to endorse the practice of switching antipsychotics for the treatment of antipsychotic-related weight gain. Finally, there continue to be major gaps in our knowledge, including limited information on (1) the use of adjunctive pharmacological agents for the treatment of persistent positive symptoms or other symptom domains of psychopathology, including anxiety, cognitive impairments, depressive symptoms, and persistent negative symptoms and (2) the treatment of co-occurring substance or medical disorders that occur frequently in individuals with schizophrenia.

Genome-wide association study of antipsychotic-induced parkinsonism severity among schizophrenia patients

RATIONALE

Antipsychotic-induced parkinsonism (AIP) is a severe adverse affect of neuroleptic treatment. Interindividual heterogeneity in AIP development and severity is associated with risk factors such as antipsychotic drug type, old age, and female gender. There is evidence for genetic predisposition to develop AIP but the variants that confer susceptibility or protection are mostly unknown.

OBJECTIVE

To identify genes related to AIP susceptibility, we performed a pharmacogenomic genome-wide association study (GWAS) for AIP severity.

METHODS

Three hundred ninety-seven American schizophrenia patients who participated in the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE)-GWAS project were included in our analysis. Patients had been randomized to treatment with antipsychotic monotherapy for periods ranging from 2 weeks to 18 months during phase 1 of the CATIE trial. They were regularly assessed for AIP severity using the modified Simpson-Angus Scale (SAS). For statistical analysis, patients were dichotomized as cases (average SAS mean global score > 0.3 during CATIE phase 1, N = 199) or controls (average SAS mean global score 0, N = 198).

RESULTS

Using logistic regression and controlling for population stratification, age, gender, SAS score at baseline, and concomitant use of anticholinergic drugs, we identified several single-nucleotide polymorphisms associated with AIP severity. Although none reached the GWAS significance level of P < 4.2 x 10(-7), some promising candidate genes for further research on genetic predisposition to AIP were identified including EPF1, NOVA1, and FIGN.

CONCLUSIONS

Our finding may contribute to understanding of the pathophysiology of AIP as well as to a priori identification of patients vulnerable for development of AIP.

Clinical and economic ramifications of switching antipsychotics in the treatment of schizophrenia

BACKGROUND

Switching between antipsychotic medications is common in the treatment of schizophrenia. However, data on clinical and economic outcomes from antipsychotic switching, in particular acute care service use, is fairly limited. The goal of this research was to assess the clinical and economic ramifications of switching antipsychotics during outpatient management of schizophrenia.

METHODS

Data from a 1-year randomized, open-label cost-effectiveness study involving typical and atypical antipsychotics were assessed. The study protocol permitted switching of antipsychotics when clinically warranted. The risk of crisis-related events, use of acute-care services, and the time to the initial use of such services were determined in outpatients who switched antipsychotics compared with those who continued with their initial medications. Health care resource utilization data were abstracted from medical records and other sources (e.g., patient self-report), and direct costs were estimated using previously published benchmarks.

RESULTS

Almost one-third of patients (29.3%) underwent a switch from their initial antipsychotic agent, with an average duration of 100 days before such treatment alterations. Compared with their counterparts who remained on their initial therapies, individuals who switched antipsychotics experienced a significantly higher risk of acute-care services, including hospitalization (p = .013) and crisis services (p = .011). Patients undergoing medication switches also used acute-care services significantly sooner (p = .004) and accrued an additional $3,000 (a 25% increase) in annual total health care costs per patient, most of which was due to acute-care expenditures.

CONCLUSION

Switching antipsychotic medications was found to be associated with considerably poorer clinical and economic outcomes, as reflected by, more frequent and more rapid use of acute-care services compared with persons remaining on their initial treatments.

TRIAL REGISTRATION

Trial ID 2325 in LillyTrials.com (also accessible via ClinicalStudyResults.org).

Methodological issues in assessing changes in costs pre- and post-medication switch: a schizophrenia study example

Background

Schizophrenia is a severe, chronic, and costly illness that adversely impacts patients' lives and health care payer budgets. Cost comparisons of treatment regimens are, therefore, important to health care payers and researchers. Pre-Post analyses ("mirror-image"), where outcomes prior to a medication switch are compared to outcomes post-switch, are commonly used in such research. However, medication changes often occur during a costly crisis event. Patients may relapse, be hospitalized, have a medication change, and then spend a period of time with intense use of costly resources (post-medication switch). While many advantages and disadvantages of Pre-Post methodology have been discussed, issues regarding the attributability of costs incurred around the time of medication switching have not been fully investigated.

Methods

Medical resource use data, including medications and acute-care services (hospitalizations, partial hospitalizations, emergency department) were collected for patients with schizophrenia who switched antipsychotics (n = 105) during a 1-year randomized, naturalistic, antipsychotic cost-effectiveness schizophrenia trial. Within-patient changes in total costs per day were computed during the pre- and post-medication change periods. In addition to the standard Pre-Post analysis comparing costs pre- and post-medication change, we investigated the sensitivity of results to varying assumptions regarding the attributability of acute care service costs occurring just after a medication switch that were likely due to initial medication failure.

Results

Fifty-six percent of all costs incurred during the first week on the newly initiated antipsychotic were likely due to treatment failure with the previous antipsychotic. Standard analyses suggested an average increase in cost-per-day for each patient of $2.40 after switching medications. However, sensitivity analyses removing costs incurred post-switch that were potentially due to the failure of the initial medication suggested decreases in costs in the range of $4.77 to $9.69 per day post-switch.

Conclusion

Pre-Post cost analyses are sensitive to the approach used to handle acute-service costs occurring just after a medication change. Given the importance of quality economic research on the cost of switching treatments, thorough sensitivity analyses should be performed to identify the impact of crisis events around the time of medication change.

Switching from risperidone to olanzapine in a one-year, randomized, open-label effectiveness study of schizophrenia

OBJECTIVE

Switching medications is common in the treatment of schizophrenia. This study examines the effectiveness of olanzapine therapy following a clinically warranted switch from risperidone during treatment of patients with schizophrenia.

RESEARCH DESIGN AND METHODS

This post-hoc analysis used data from the risperidone arm of a randomized, open-label, 1-year study of patients with schizophrenia. Study protocol permitted antipsychotic switching when clinically warranted, and outcomes were assessed with standard psychiatric measures. Statistical analyses assessed changes from pre- to post-medication switch and endpoint comparisons between patients switched from risperidone to olanzapine and patients continued on risperidone.

RESULTS

Most patients who switched from risperidone switched to olanzapine (43/60; 71.7%). Average duration of risperidone treatment prior to switching was 86 days (mean modal dose 4.0 mg/day). Most switchers (86%) completed the 1-year study on olanzapine (average duration 241 days; mean modal dose 12.0 mg/day). Following switch to olanzapine, patients experienced significant improvements on clinical (Brief Psychiatric Rating Scale) and social (Quality of Life Inventory) parameters, with similar proportions of patients achieving remission status at endpoint compared with risperidone patients not requiring medication switch (41.9 vs. 35.5%). Mean weight gain for switchers was approximately 0.4 kg while on risperidone (average treatment duration < 3 months) and 2.4 kg on olanzapine (average treatment duration approximately 8 months).

CONCLUSIONS

This study suggests that olanzapine is an effective treatment option for schizophrenia patients requiring a switch from risperidone. Given the small sample size and lack of a comparative group, one cannot determine if other medication options would have been as effective as the switch to olanzapine. Thus, further research is warranted.

Association of the RGS2 gene with extrapyramidal symptoms induced by treatment with antipsychotic medication

OBJECTIVES

To investigate the role of genes encoding regulators of G protein signaling in early therapeutic response to antipsychotic drugs and in susceptibility to drug-induced extrapyramidal symptoms. As regulators of G protein signaling and regulators of G protein signaling-like proteins play a pivotal role in dopamine receptor signaling, genetically based, functional variation could contribute to interindividual variability in therapeutic and adverse effects.

METHODS

Consecutively hospitalized, psychotic patients with Diagnostic and Statistical Manual of Mental Disorder-IV schizophrenia (n=121) were included in the study if they received treatment with typical antipsychotic medication (n=72) or typical antipsychotic drugs and risperidone (n=49) for at least 2 weeks. Clinical state and adverse effects were rated at baseline and after 2 weeks. Twenty-four single nucleotide polymorphisms were genotyped in five regulators of G protein signaling genes.

RESULTS

None of the single nucleotide polymorphisms were related to clinical response to antipsychotic treatment at 2 weeks. Five out of six single nucleotide polymorphisms within or flanking the RGS2 gene were nominally associated with development or worsening of parkinsonian symptoms (PARK+) as measured by the Simpson Angus Scale, one of them after correction for multiple testing (rs4606, P=0.002). A GCCTG haplotype encompassing tagging single nucleotide polymorphisms within and flanking RGS2 was significantly overrepresented among PARK+ compared with PARK--patients (0.23 vs. 0.08, P=0.003). A second, 'protective', GTGCA haplotype was significantly overrepresented in PARK--patients (0.13 vs. 0.30, P=0.009). Both haplotype associations survive correction for multiple testing.

CONCLUSIONS

Subject to replication, these findings suggest that genetic variation in the RGS2 gene is associated with susceptibility to extrapyramidal symptoms induced by antipsychotic drugs.

The stable patient with schizophrenia--from antipsychotic effectiveness to adherence

Long-term treatment of stable schizophrenia focuses on treatment effectiveness, addressing direct efficacy plus treatment adherence, treatment burden, and impact on factors such as weight gain. With the introduction of atypical antipsychotics such as aripiprazole, reduced side effects may lead to improved long-term treatment. The Clinical Trials of Intervention Effectiveness (CATIE) study where 1500 patients were randomised to atypical antipsychotics (olanzapine, quetiapine, risperidone, ziprasidone), or the typical antipsychotic drug perphenazine showed high discontinuation rates of 74% after 18 months, but extrapyramidal side effects were lower after atypical antipsychotic treatment compared with perphenazine. Twenty-six weeks of aripiprazole treatment, assessed in 284 patients in the Schizophrenia Trial of Aripiprazole (STAR) showed that aripiprazole had similar discontinuation rates to the atypical antipsychotics standard of care. In the CATIE study, weight gain was common during treatment. In contrast, STAR demonstrated a favourable weight profile for aripiprazole, with a mean weight loss of 0.41 kg. Results from these naturalistic trials help define the effectiveness of atypical antipsychotics for long-term treatment.

Effects of switching from conventional antipsychotics to risperidone in Japanese patients with chronic schizophrenia

Atypical antipsychotics are rapidly evolving to become the standard pharmacotherapy in schizophrenia; however, the trend of switching to such drugs is not necessarily progressing quickly in East Asia. This might be due to the scarcity of evidence for the efficacy of switching from conventional to atypical antipsychotics, which prompted the authors to examine effects of switching from conventional antipsychotics to an atypical drug, risperidone, in Japanese patients. Fifty patients with chronic schizophrenia completed the study in which combination therapy with other antipsychotics was allowed if monotherapy with risperidone was not tolerated. Symptoms were assessed with the brief psychiatric rating scale (BPRS). Switching to monotherapy was achieved in 34 patients (68%). The number of antipsychotics prescribed to each patient was reduced (from 2.1 to 1.4 drugs; P < 0.001) and the use of antiparkinsonian drugs decreased (P < 0.001). The mean BPRS score was also reduced 6 months after initiation of the switch (P < 0.001). Failure in switching to monotherapy was associated with higher dosage of antipsychotics at baseline. Switching from conventional antipsychotics to risperidone reduced schizophrenia symptoms, antiparkinsonian medication, and polypharmacy. However, a portion of patients, particularly those who receive an excessive dosage of antipsychotics, might not tolerate such switching.

Reducing Polypharmacy Through the Introduction of a Treatment Algorithm: Use of a Treatment Algorithm on the Impact on Polypharmacy

Introduction: Polypharmacy is very common in the psychiatric setting despite the lack of evidence to justify its use. The objective of this study was to review the prescription patterns in a tertiary mental health institute in Asia and evaluate the impact of a treatment algorithm for patients with first-episode psychosis (FEP) on the use of polypharmacy. Materials and Methods: A treatment algorithm was implemented for patients accepted into an Early Psychosis Intervention Programme (EPIP) and the prescription patterns of these patients were compared with a comparator group (pre-EPIP) before the use of the algorithm. The prescribing pattern was established at 2 points: at baseline after the diagnosis was made, and 3 months later. Results: There were 68 subjects in the comparator group and 483 EPIP patients; the latter were on the average younger. None in the comparator group was diagnosed to have an affective psychosis. There was a significant reduction in the rate of antipsychotic polypharmacy, prolonged use of benzodiazepines and anticholinergic medication in EPIP patients. This group also had an increase in the use of second-generation antipsychotics and received lower doses of antipsychotics. Conclusion: The implementation of a treatment algorithm coupled with audit has changed the trend towards polypharmacy among patients with FEP. Key words: Antipsychotics, Drug use review, Psychosis

Switching antipsychotics: an updated review with a focus on quetiapine

Atypical antipsychotics offer broader efficacy and improved tolerability compared with conventional agents. Many patients currently treated with conventional antipsychotics continue to experience persistent symptoms or troublesome side effects and may benefit from a change to one of the newer atypical agents. There are also significant differences in the side-effect profiles of the atypicals, such that a switch from one atypical agent to another could offer advantages to many patients. Unfortunately, many clinicians remain uncertain about the switching process and are reluctant to initiate change. The aim of this review is to identify the indications for a switch in antipsychotic therapy with a focus on recent switching data for the atypical antipsychotic, quetiapine. The clinical aspects of quetiapine's receptor binding characteristics are reviewed including the implications of the low D(2) antagonist properties that make quetiapine the treatment of choice when EPS persists with other atypical antipsychotics. Practical guidelines are given for managing the process of changeover, for avoiding pitfalls and for maximizing the chances of a successful switch. For example, when managing the antipsychotic crossover, it is important to consider the psychological effects of switching arising from symptom and side-effect changes. Finally, advice is provided on the assessments necessary when evaluating the success of a change in therapy, together with guidance on the optimal duration of treatment trials.