Low continuation of antipsychotic therapy in Parkinson disease - intolerance, ineffectiveness, or inertia?

Brief commentary: Under-recognition of underuse of clozapine in treating psychotic symptoms in Parkinson's disease

Clozapine is an important drug in the treatment of Parkinson's disease (PD). It has proven efficacy in treating PD psychosis without worsening motor function, as well as in treating tremor refractory to L-Dopa, yet it is severely underused in the United States. Unlike the situation of treatment resistant schizophrenia, this underuse is underrecognized.

Parkinson's disease psychosis management: an evidence based, experience informed, pragmatic approach

INTRODUCTION

Psychotic symptoms in people with Parkinson's disease (PD) have attracted increasing. Recommendations on treating psychosis often fail to take into account what psychotic symptoms require treatment, which has been complicated by the increasing number of reports documenting the frequency of 'minor' hallucinations.

AREAS COVERED

This article focuses both on the phenomenology of psychotic symptoms and their management.

EXPERT OPINION

Understanding the nature and implications of the types of psychotic symptoms in PD is the key to proper treatment. Evidence and experience-based data on the effect of anti-psychotic medications will be reviewed and how the various clinical settings should determine the treatment approach. The evidence base consists of all reported blinded trials recorded in PubMed and the experience-based studies are those chosen by the author from PubMed as illustrative. Specific recommendations for the treatment of psychosis will be listed for specific situations. Pimavanserin is the first-line choice for mild symptoms; quetiapine for symptoms that require improvement in a short period and clozapine for urgent problems or those which fail the other approaches.

Clinical Evaluation of Sleep Disorders in Parkinson’s Disease

The paradigm of the framing of Parkinson’s disease (PD) has undergone significant revision in recent years, making this neurodegenerative disease a multi-behavioral disorder rather than a purely motor disease. PD affects not only the “classic” substantia nigra at the subthalamic nuclei level but also the nerve nuclei, which are responsible for sleep regulation. Sleep disturbances are the clinical manifestations of Parkinson’s disease that most negatively affect the quality of life of patients and their caregivers. First-choice treatments for Parkinson’s disease determine amazing effects on improving motor functions. However, it is still little known whether they can affect the quantity and quality of sleep in these patients. In this perspective article, we will analyze the treatments available for this specific clinical setting, hypothesizing a therapeutic approach in relation to neurodegenerative disease state.

Comparison of Pimavanserin Versus Quetiapine for Hospitalization and Mortality Risk Among Medicare Beneficiaries with Parkinson's Disease Psychosis

Background

Pimavanserin is currently the only antipsychotic approved for Parkinson's disease (PD) psychosis, yet its relative safety compared with treatment alternatives has not been thoroughly assessed.

Objectives

This study aimed to compare hospitalization and mortality risk in Medicare beneficiaries with PD receiving new prescriptions of pimavanserin or quetiapine for PD psychosis.

Methods

The study identified new users of pimavanserin and quetiapine from a 15% national sample of Medicare fee-for-service claims collected between May 1, 2016, and December 30, 2018. All-cause hospitalization and mortality were assessed in time-to-event regression models. Standardized mortality ratio weighting balanced pimavanserin and quetiapine users on baseline characteristics. Follow-up was censored at discontinuation, switch, disenrollment, or the end of the study period.

Results

There were 844 new pimavanserin users and 2505 new quetiapine users. The adjusted hazard ratios (95% confidence intervals [CIs]) for hospitalization at 30, 90, 180, and 365 days for pimavanserin versus quetiapine users were 0.59 (0.43-0.81), 0.56 (0.44-0.72), 0.63 (0.52-0.77), and 0.70 (0.60-0.83). The most common reasons for hospitalization were traumatic injury and sepsis. Hospitalizations for heart-related issues were higher with pimavanserin (P < 0.05). The adjusted hazard ratios (95% CIs) for all-cause mortality at 90, 180, and 365 days for pimavanserin versus quetiapine users were 0.73 (0.48-1.13), 0.80 (0.58-1.10), and 0.94 (0.74-1.19).

Conclusions

Risk of hospitalization was lower in pimavanserin users compared with quetiapine, and no difference in mortality was observed between pimavanserin and quetiapine. An active comparator analyses with treatment alternatives provided the most clinically relevant information for patients and physicians.

Channeling of New Neuropsychiatric Drugs-Impact on Safety and Effectiveness Studies

This study aimed to examine differential prescribing due to channeling and propensity score non-overlap over time in new versus established treatments for common neurological conditions. We conducted cross-sectional analyses on a national sample of US commercially insured adults using 2005-2019 data. We compared new users of recently approved versus established medications for management of diabetic peripheral neuropathy (pregabalin versus gabapentin), Parkinson disease psychosis (pimavanserin versus quetiapine), and epilepsy (brivaracetam versus levetiracetam). Within these drug pairs, we compared demographic, clinical, and healthcare utilization characteristics of recipients of each drug. In addition, we fit yearly propensity score models for each condition and assessed propensity score non-overlap over time. For all three drug pairs, users of the more recently approved medications more frequently had prior treatment (pregabalin = 73.9%, gabapentin = 38.7%; pimavanserin = 41.1%, quetiapine = 14.0%; brivaracetam = 93.4%, levetiracetam = 32.1%). Propensity score non-overlap and its resulting sample loss after trimming were the greatest in the first year that the more recently approved medication was available (diabetic peripheral neuropathy, 12.4% non-overlap; Parkinson disease psychosis, 6.1%; epilepsy, 43.2%) and subsequently improved. Newer neuropsychiatric therapies appear to be channeled to individuals with refractory disease or intolerance to other treatments, leading to potential confounding and biased comparative effectiveness and safety study findings when compared to established treatments. Propensity score non-overlap should be reported in comparative studies that include newer medications. When studies comparing newer and established treatments are critically needed as soon as new treatments enter the market, investigators should recognize the potential for channeling bias and implement methodological approaches like those demonstrated in this study to understand and improve this issue in such studies.

Mortality in Patients with Parkinson's Disease-Related Psychosis Treated with Pimavanserin Compared with Other Atypical Antipsychotics: A Cohort Study

INTRODUCTION

Pimavanserin is approved in the USA to treat hallucinations and delusions associated with Parkinson's disease psychosis (PDP).

OBJECTIVES

We evaluated mortality in patients with PDP after initiation of pimavanserin or comparator atypical antipsychotics, overall, over time, and across subgroups.

METHODS

A cohort of patients aged ≥65 years in the USA with PDP newly initiating pimavanserin or a comparator atypical antipsychotic (clozapine, quetiapine, risperidone, olanzapine, aripiprazole, brexpiprazole) was identified in 2016-2019 Medicare claims data. All-cause mortality in the propensity score-matched treatment groups was compared with hazard ratios (HRs) and 95% confidence intervals (CIs) estimated with Cox-proportional hazards models. Cumulative incidence curves and time period-specific models evaluated risk over time. Subgroup and sensitivity analyses were performed, including a sub-cohort of long-term care (LTC) or skilled nursing facility (SNF) residents.

RESULTS

We identified 2892 pimavanserin initiators and 19,083 comparator initiators (overall 47% female, mean age = 80.9 years, LTC/SNF residents = 30%). Before matching, pimavanserin users had fewer severe comorbidities and more anti-Parkinson medication use than comparators. Matching resulted in 2891 patients in both groups, and all covariates were well balanced. In the matched cohort, the HR for mortality for pimavanserin versus comparator was 0.78 (95% CI 0.67-0.91), with the lowest time period-specific HRs in the first 180 days. Hazard ratios were similar across sensitivity analyses and subgroups. In LTC/SNF residents, the HR was 0.78 (95% CI 0.60-1.01).

CONCLUSION

The observed mortality rates were lower among patients treated with pimavanserin compared with those treated with other atypical antipsychotics.

STUDY REGISTRATION

European Union Post-authorization Study (EU PAS) register number 46331.

Atypical antipsychotic use and mortality risk in Parkinson disease

INTRODUCTION

Dopamine receptor blocking atypical antipsychotic (DRB-AAP) use has previously been associated with increased adverse effects and mortality risk among persons with Parkinson disease (PD). Pimavanserin, the only AAP indicated for PD psychosis in the U.S., is a serotonin receptor inverse agonist/antagonist with no known DRB activity. Early observational data have reported inconsistent findings regarding mortality risk associated with pimavanserin. The objective of this study was to estimate all-cause mortality risks of pimavanserin as compared to DRB-AAPs.

METHODS

We conducted a retrospective cohort study using a large U.S. commercial insurance database. Cox proportional hazards models were used to compare all-cause mortality risks between propensity score-matched groups of PD patients who were new users of pimavanserin or a DRB-AAP, further dividing DRB-AAPs into preferred (quetiapine, clozapine) and non-preferred (other remaining AAPs).

RESULTS

We identified 775, 4,563, and 1,297 individuals on pimavanserin, preferred, and non-preferred DRB-AAPs, respectively. There was no difference in mortality risk for pimavanserin vs. preferred DRB-AAPs [adjusted hazard ratio (aHR) 0.99, 95% CI: 0.81-1.20], or pimavanserin vs. non-preferred DRB-AAPs (aHR 0.98, 95% CI: 0.79-1.22) in intention-to-treat analyses.

CONCLUSION

Mortality risk among PD patients using AAPs did not differ by antipsychotic drug categorization based on mechanism of action. Research on the comparative efficacy and morbidity of AAPs, and the mortality associated with psychosis itself is needed to guide clinical decision-making in the PD population.

Clozapine Use in a Movement Disorder Clinic

BACKGROUND

Clozapine is an effective antipsychotic for Parkinson's disease (PD) that does not worsen motor function and can improve tremor. It is approved for PD psychosis in Europe and Australia.

OBJECTIVE

The aim of this study was to report on the use of clozapine in a movement disorder clinic.

METHODS

We report on patients monitored during the COVID-19 pandemic in clinic over a 7-month period.

RESULTS

Sixty-five patients were seen, of whom 50 had PD. Thirty-one were treated for psychosis, 18 for refractory tremor and 1 for levodopa dyskinesias. The remainder had psychotic symptoms with dementia with Lewy bodies (n = 2) or other movement disorders. Four had clozapine discontinued because of sedation and 1 for agranulocytosis. Three had clozapine temporarily halted because of granulocytopenia but were rechallenged successfully.

CONCLUSIONS

When comparing clozapine use in this clinic as compared with others, we deduce that clozapine is likely significantly underutilized in the United States.

Long-term outcomes with pimavanserin for psychosis in clinical practice

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Psychosis in PD is a common problem, with limited treatment options.

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Pimavanserin is FDA approved for PDP, but long-term outcomes in clinical practice are lacking.

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While it has been proven to be effective in short-duration clinical trials, our clinical experiences, however, demonstrate less promising results in the long term.

Introduction

Pimavanserin is the only medication FDA-approved for the treatment of Parkinson disease (PD) psychosis (PDP), but reports of long-term, real-world clinical experience are lacking.

Methods

A retrospective chart review of all patients treated with pimavanserin was conducted at our large Movement Disorders practice in Providence, Rhode Island, USA. Demographic and clinical data for each patient were collected and descriptive analyses were performed.

Results

We identified 54 patients (23 female) who initiated pimavanserin, whose median age was 70 years (range 44–87 years) and the median duration of pimavanserin therapy was 26 weeks. Initial improvement was seen in 47% of the entire group, and 50% of the DLB patients. Additional antipsychotic medication was needed concomitantly with pimavanserin to maintain a positive response for 40% of patients. Only 15% of the entire group had effective treatment of their condition with pimavanserin monotherapy over a median of 52 weeks. Among the initial responders, 32% continued on pimavanserin monotherapy. Among the non-responders, the mean trial period for patients who did not improve was 27 weeks, for patients who worsened was 16 weeks, and for those who experienced adverse effects was 1–2 weeks. Reported sex was similar across responders (60%), non-responders (56%), and the overall cohort (57%).

Conclusion

Our real-world experience shows that pimavanserin is safe and tolerable, with a lower response rate than reported in other publications. While it has been proven to be effective in short-duration clinical trials, our clinical experiences, however, demonstrate less promising results in the long term.