Co-prescribing of SSRIs and TCAs in Australia: how often does it occur and who is doing it?

Factors associated with sick leave duration in patients suffering from major depressive disorder initiating antidepressant treatment: a real-world evidence study in Germany and Spain

OBJECTIVE

To describe MDD patients starting antidepressant (AD) treatment by pharmacological approach and identify factors associated with a longer sick leave (SL) duration.

METHODS

Retrospective study on IQVIA German Disease Analyser (specialists) and Spanish Longitudinal Patient Database (general practitioners and specialists). MDD patients initiating AD treatment between July 2016-June 2018 were grouped by therapeutic approach (AD monotherapy vs. combination/switch/add-on) and their characteristics were analysed descriptively. Multiple logistic regression models were run to evaluate factors affecting SL duration (i.e., >30 days).

RESULTS

One thousand six hundred and eighty-five patients (monotherapy: 58%; combination/switch/add-on: 42%) met inclusion criteria for Germany, and 1817 for Spain (monotherapy: 83%; combination/switch/add-on: 17%). AD treatment influenced SL duration: combination/switch/add-on patients had a 2-fold and a 4-fold risk of having >30 days of SL than monotherapy patients, respectively in Germany and Spain. Patients with a gap of time between MDD diagnosis and AD treatment initiation had a higher likelihood of experiencing a longer SL both in Germany and Spain (38% higher likelihood and 6-fold risk of having >30 days of SL, respectively).

CONCLUSIONS

A careful and timely selection of AD treatment approach at the time of MDD diagnosis may improve functional recovery and help to reduce SL, minimising the socio-economic burden of the disease.Key pointsThe major depressive disorder has a substantial impact on work absenteeism.The present study aimed to describe MDD patients starting antidepressant (AD) treatment depending on the pharmacological approach and to identify factors associated with longer sick leave (SL) duration.Patients receiving AD monotherapy had a lower likelihood of having more than 30 days of sick leave than those receiving AD combination/switch/add-on.Patients for whom a gap of time between MDD diagnosis and initiation of AD treatment was observed, showed a higher likelihood of having more than 30 days of sick leave.Because findings from this analysis relied on secondary data, the authors would like to claim the urgency of conducting prospective observational studies that further investigate the effect that different AD therapeutic approaches and timely initiation of treatment might exert on patients' recovery.

Psychotropic polypharmacy in Australia, 2006 to 2015: a descriptive cohort study

AIMS

To describe psychotropic polypharmacy in Australia between 2006 and 2015.

METHODS

We used pharmaceutical claims from a national 10% sample of people with complete dispensing histories to estimate the annual prevalence of the combined use (overlap of >60 days exposure) of ≥2 psychotropics overall and within the same class or subclass (class and subclass polypharmacy). We also estimated the proportion of polypharmacy episodes involving one, two, three and four or more unique prescribers.

RESULTS

The prevalence of class polypharmacy between 2006 and 2015 in people dispensed specific psychotropic classes was 5.9-7.3% for antipsychotics, 2.1-3.7% for antidepressants and 4.3-2.9% for benzodiazepines. The prevalence of antipsychotic polypharmacy was higher than expected given the prevalence of antipsychotic exposure and combinations of sedating agents were notably common. Overall, 26.7% of polypharmacy episodes involved multiple prescribers but having multiple prescribers occurred more frequently for class and subclass polypharmacy and people with four or more concomitant psychotropics.

DISCUSSION

Psychotropic polypharmacy is common, despite limited evidence of risks and benefits. Increases in polypharmacy with multiple prescribers may be due to poor communication with patients and between health care professionals.

The Risk of Hip Fracture Due to Mirtazapine Exposure When Switching Antidepressants or Using Other Antidepressants as Add-On Therapy

Background

Antidepressants are associated with adverse effects such as sedation and hypotension, which can result in falls and fractures. Few studies have assessed the risk of hip fracture due to mirtazapine, and no known studies have assessed whether the risk of hip fracture is higher in patients taking other antidepressant medicines in combination with mirtazapine.

Objectives

This study aimed to examine the risk of hip fracture in older people due to mirtazapine use as well as switching between or concurrently using mirtazapine and other antidepressants.

Method

A matched case–control study was conducted. Cases were people aged over 65 years who were eligible for Australian Government Department of Veterans’ Affairs (DVA) benefits and who sustained a hip fracture between 2009 and 2012. Each case was matched with up to four randomly selected controls of the same gender and age (± 2 years). Multivariable conditional logistic regression was used to estimate associations between antidepressant use and hip fracture. In order to assess whether combined antidepressant effects differed from the sum of individual effects, the relative excess risk due to interaction (RERI) was calculated.

Results

The study population comprised 8828 cases and 35,310 controls. The median age of these participants was 88 years and 63% were women. The risk of hip fracture was increased for mirtazapine (continuous use: odds ratio [OR] 1.27, 95% confidence interval [CI] 1.12–1.44). The combinations associated with increased odds of hip fracture were addition of selective serotonin reuptake inhibitors (SSRIs) to mirtazapine (OR 11, 95% CI 2.2–51; RERI 7.7, 95% CI −9.0 to 24), addition of tricyclic antidepressants (TCAs) to mirtazapine (OR 14, 95% CI 1.4–132; RERI 12, 95% CI −19 to 43) and continuous use of both SSRIs and mirtazapine (OR 2.4, 95% CI 1.4–4.2; RERI 0.4, 95% CI −0.9 to 1.7). RERIs indicated that the effect of each antidepressant pair equalled the sum of the effects of individual antidepressant use. There was no evidence of dispensing of lower strength mirtazapine upon introducing TCAs and SSRIs.

Conclusions

Our results show elevated risk of hip fracture following use of mirtazapine alone and in combination with other antidepressants. The overlapping use of antidepressants may reflect the treatment of comorbidities (e.g. anxiety), switching from mirtazapine to other antidepressants, or add-on therapy. Our results highlight the risks of employing add-on therapy or switching antidepressants in older people, providing further evidence to support cautious cross-tapering where switching between antidepressants is required.

Electronic supplementary material

The online version of this article (doi:10.1007/s40801-017-0120-y) contains supplementary material, which is available to authorized users.

[Prevalence of Avoidable Potential Interactions Between Antidepressants and Other Drugs in Colombian Patients]

OBJECTIVES

To determine the possible drugs interactions with antidepressive agents in data bases of patients in the Health Insurance System of Colombia.

METHODS

From data bases of about 4 million users in Colombia, a systematic review of drugs dispensation statistics was made to identify drug interactions between antidepressive agents, cholinergic antagonists and tramadol in 2010.

RESULTS

We identified 114,465 monthly users of antidepressive agents. Of these, 5776 (5.0%) received two, and 178 (0.2%) received three antidepressive agents simultaneously. The most frequent combination was fluoxetine+trazodone (n=3235; 56.9% of cases). About 1127 (1.0%) patients were prescribed a cholinergic antagonist simultaneously; 2523 (2.1%) users were dispensed tramadol at the same time, while raising the risk of serotonin syndrome.

CONCLUSIONS

Drug interactions represent a potential risk that is often underestimated by physicians. Pharmacovigilance is a useful tool to optimize resources and prevent negative outcomes associated with medication. It is recommended that systematic search is made to enhance surveillance programs for the rational use of medicines in this country.

Validation and application of a death proxy in adult cancer patients

PURPOSE: Fact of death is not always available on data sets used for pharmacoepidemiological research. Proxies may be an appropriate substitute in the absence of death data. The purposes of this study were to validate a proxy for death in adult cancer patients and to assess its performance when estimating survival in two cohorts of cancer patients. METHODS: We evaluated 30-, 60-, 90- and 180-day proxies overall and by cancer type using data from 12 394 Australian veterans with lung, colorectal, breast or prostate cancer. The proxy indicated death if the difference between the last dispensing record and the end of the observational period exceeded the proxy cutoff. We then compared actual survival to 90-day proxy estimates in a subset of 4090 veterans with 'full entitlements' for pharmaceutical items and in 3704 Australian women receiving trastuzumab for HER2+ metastatic breast cancer. RESULTS: The 90-day proxy was optimal with an overall sensitivity of 99.3% (95%CI: 98.4-99.7) and a specificity of 97.6% (95%CI: 91.8-99.4). These measures remained high when evaluated by cancer type and spread of disease. The application of the proxy using the most conservative date of death estimate (date of last dispensing) generally underestimated survival, with estimates up to 3 months shorter than survival based on fact of death. CONCLUSIONS: A 90-day death proxy is a robust substitute to identify death in a chronic population when fact of death is not available. The proxy is likely to be valid across a range of chronic diseases as it relies on the presence of 'regular' dispensing records for individual patients. Copyright © 2011 John Wiley & Sons, Ltd.

The strategy of combining antidepressants in the treatment of major depression: clinical experience in spanish outpatients

Introduction. The combination of antidepressants is a useful tool in the treatment of major depression, especially in cases where there is a partial response to antidepressant monotherapy. However, the use of this strategy is a matter of controversy, and its frequency of use in clinical practice is not clear. The aim of our study is to assess the use of antidepressants combination in Spain by reviewing three databases used between 1997 and 2001. Methods. Databases pertain to patients who are study subjects of major depression treatment. These databases are a result of studies performed in Spain and in which 550 psychiatrists participated. The total studied sample was comprised of N = 2, 842 patients, aged over 18, fitting DSM-IV criteria for Major Depressive Episode. The percentage of patients who received more than one antidepressant and the types of combinations used was described. Subsequently, a comparative study between the group which received a combination of antidepressants (N = 64) and the group which received antidepressant monotherapy (N = 775) was performed. Results. 27.1% of patients were on antidepressive monotherapy treatment, and 2.2% were on combination therapy. In the comparison of patients on combination therapy and monotherapy, there were significant differences only in episode duration (P = 0.001). The most frequent combinations are SSRIs and tricyclic antidepressants. The active principle most widely combined is fluoxetine. Conclusions. The prevalence of use of antidepressant combination therapy is 2.2% of the global sample and 8.3% of treated patients. Other than duration of the depressive episode, no clinical characteristics exclusive to patients who received combination rather than monotherapy were found. Our study found that the most frequent combination is SSRIs + TCAs, also being the most studied.

Uncovering the potential risk of serotonin toxicity in Australian veterans using pharmaceutical claims data

AIMS

We examined potential risk of serotonin toxicity in Australian veterans by quantifying the concomitant use of serotonergic medicine combinations from claims data collected by the Department of Veterans' Affairs (DVA).

METHODS

This was a retrospective cohort study of 273 228 Australian veterans, war widows, widowers and dependents aged >or=55 years and holding full treatment entitlement for the period July 2000 to June 2004 or until death. The main outcome measure was potential concomitant use, estimated as the number of cohort members with an overlap in days of supply for serotonergic medicine combinations over the 4 year period for all medicine combinations and potentially life threatening combinations.

RESULTS

From July 2000 to June 2004, 115 969 (42%) cohort members were dispensed at least one serotonergic medicine. 20 658 (8%) had at least one episode of potential concomitant use. We identified 1811 (0.7%) cohort members with at least one overlapping period of potentially life-threatening serotonergic medicine combinations, 937 of whom had the combinations dispensed within the recommended washout period. Three hundred and seventeen of these individuals were dispensed potentially life-threatening medicine combinations on the same day. The most common combinations were moclobemide with a selective serotonin reuptake inhibitor or tramadol.

CONCLUSIONS

The individuals potentially at risk of mild to moderate serotonin toxicity were considerable and potentially life threatening combinations were not infrequent. While we were unable to determine how many individuals experienced serotonin toxicity this study indicates, for the first time, the potential size of the problem in a subgroup of elderly Australians. Clinicians and patients need to be vigilant regarding inadvertent concomitant use, especially that of moclobemide with a selective serotonin reuptake inhibitor or tramadol.

Tricyclic antidepressant pharmacology and therapeutic drug interactions updated

New data on the pharmacology of tricyclic antidepressants (TCAs), their affinities for human cloned CNS receptors and their cytochrome P450 enzyme inhibition profiles, allow improved deductions concerning their effects and interactions and indicate which of the TCAs are the most useful. The relative toxicity of TCAs continues to be more precisely defined, as do TCA interactions with selective serotonin reuptake inhibitors (SSRIs). TCA interactions with monoamine oxidase inhibitors (MAOIs) have been, historically, an uncertain and difficult question, but are now well understood, although this is not reflected in the literature. The data indicate that nortriptyline and desipramine have the most pharmacologically desirable characteristics as noradrenaline reuptake inhibitors (NRIs), and as drugs with few interactions that are also safe when coadministered with either MAOIs or SSRIs. Clomipramine is the only available antidepressant drug that has good evidence of clinically relevant serotonin and noradrenaline reuptake inhibition (SNRI). These data assist drug selection for monotherapy and combination therapy and predict reliably how and why pharmacodynamic and pharmacokinetic interactions occur. In comparison, two newer drugs proposed to have SNRI properties, duloxetine and venlafaxine, may have insufficient NRI potency to be effective SNRIs. Combinations such as sertraline and nortriptyline may therefore offer advantages over drugs like venlafaxine that have fixed ratios of SRI/NRI effects that are not ideal. However, no TCA/SSRI combination is sufficiently safe to be universally applicable without expert knowledge. Standard texts (e.g. the British National Formulary) and treatment guidelines would benefit by taking account of these new data and understandings.

Antidepressants: prevalence of duplicate therapy and avoidable drug interactions in Australian veterans

OBJECTIVE

This study assessed the prevalence of duplicate antidepressant prescribing and avoidable potential antidepressant drug interactions in the Australian war veteran population.

METHOD

The Department of Veterans' Affairs Pharmacy Claims database was interrogated, using specific criteria, to identify antidepressant duplication. In addition, potential drug interactions where safer alternative therapies were available were assessed. These included anticholinergic agents with tricyclic antidepressants and tramadol with antidepressants. Episodic tramadol dispensings with antidepressants were also assessed.

RESULTS

A total of 46,859 veterans had antidepressants regularly dispensed to them in the period 1 April-31 July 2005. Overall, 4037 potential interactions were identified in 3818 veterans (8.1%) to whom were dispensed antidepressants regularly. Antidepressant and tramadol co-prescribing was the most common potential interaction identified among 3.6% of veterans. Two or more interactions were identified in 212 veterans (0.5%). Analysis of episodic tramadol dispensings with antidepressants suggested a much higher prevalence of 7.7%.

CONCLUSION

The increasing use of antidepressants and the high level of potentially avoidable interactions detected in the present study, highlight the necessity of ongoing vigilance concerning the use of potentially inappropriate drug combinations, particularly in the elderly.

Combined antidepressants: clinical experience

OBJECTIVE

To review the current literature on the use of combinations of antidepressive agents.

METHOD

Literature searches were undertaken and reviewed on the use of combinations of antidepressants.

RESULTS

Data sources included surveys, analyses of prescription records, decision algorithms, clinical reports, and studies comparing the monotherapy with combination therapy. More recent surveys recommend combining different selective serotonin reuptake inhibitors (SSRIs), an SSRI plus bupropion or dual action antidepressants plus an SSRI. Decision algorithms recommend an SSRI plus tricyclic antidepressant (TCA) and more recently bupropion plus venlafaxine or mirtazapine. Few controlled clinical trials comparing the combined therapy with monotherapy have been conducted. Beneficial effects have been reported with combinations of TCAs plus mianserin or SSRIs plus mirtazapine.

CONCLUSION

Adding or combining antidepressant medications has advantages for the speed of onset and maintaining the existing response. More rigorous clinical trials comparing combination therapy with monotherapy and for the development of rational treatment guidelines are required.

Potential Drug–Drug Interactions in the Outpatient Setting

BACKGROUND

Although medication safety research has tended to focus on inpatients, the safety of drug use among outpatients is also a concern.

OBJECTIVE

We estimate the frequency of potentially interacting concomitant medication dispensing among outpatients.

RESEARCH DESIGN

We report the number and percent of patients annually dispensed an object drug of interest (ie, warfarin, digoxin, cyclosporine, or lovastatin/simvastatin) with a potentially interacting drug among a random sample of insured adults receiving care from 10 integrated delivery systems. We use 2 definitions of concomitant dispensing: medications dispensed: 1) during the time period for which the patient had the other medication available ('days supply') and 2) on the same day. We also estimate the number of insured U.S. population codispensed these medication pairs.

RESULTS

Among patients dispensed a drug of interest, between 17.8% (95% confidence interval [CI]=17.1-18.6%) and 28.0% (95% CI=24.0-32.1%) were concomitantly dispensed a potentially interacting drug using the "days supply" definition, and between 7.1% (95% CI=6.6-7.7%) and 17.7% (95% CI=14.4-21.1%) using the "same day" definition. Extrapolating to the insured U.S. population, between 1.29 (95% CI=1.25-1.33; same day) and 2.67 (95% CI=2.62-2.72; days supply) million insured adults are dispensed 1 of these 4 potentially interacting pairs.

CONCLUSIONS

We found evidence of potentially interacting concomitant medication dispensing among outpatients. An opportunity exists to better understand how such dispensing translates into adverse events and ultimately to improved medication safety.

Antidepressant combinations: epidemiological considerations

OBJECTIVE

To evaluate the treatment options in patients who do not respond appropriately to a single antidepressant alone.

METHOD

The medical literature was reviewed.

RESULTS

A number of strategies are available if a patient fails to respond adequately to initial antidepressant treatment, including the combination with another psychoactive drug. Evidence published to date appears to suggest that benzodiazepines are the drugs most frequently combined with antidepressants. The combination of two antidepressants together is less common, occurring in approximately 5-15% of cases showing a poor initial response. The key figures involved in such co-prescription are psychiatrists.

CONCLUSION

There appears to be considerable variability in the data concerning combined prescription of antidepressants, with differences arising depending on the type of physician, the type of patient or illness and the geographical area. It is also unclear how closely research findings parallel with what doctors do in everyday practice.

Length of therapy with selective serotonin reuptake inhibitors and tricyclic antidepressants in Australia

OBJECTIVE

To investigate the proportion of patients starting on either selective serotonin reuptake inhibitors (SSRIs) or tricyclic antidepressants (TCAs) who continued treatment for a period consistent with recommended guidelines for major depression, that is at least 6 months.

METHOD

Cohort study using a national dispensing claims database involving patients eligible for social security entitlements in Australia. Two 'new user' cohorts were established of patients who were supplied a prescription for either an SSRI (6026) or a TCA (4158) in the first week of April 2000 and who had not received a prescription for any antidepressant in the preceding three months. The main outcome measure was the proportion of patients who were still having any SSRI or TCA prescription, respectively, dispensed between 6 and 8 months after initiation. Additionally, for patients starting on either a leading SSRI (sertraline) or TCA (dothiepin), the proportions of those that remained on these drugs or had changed to other antidepressants were determined. The dispensing data are not linked to reason for prescribing in the national dataset.

RESULTS

2267 SSRI 'new users' (38%) were still receiving SSRIs 6-8 months later, compared with 1269 (31%) of the 4158 TCA 'new users' (p < 0.001). The difference between the groups occurred early, by the 2-4 month time interval. 1038 (41%) of patients starting on the individual SSRI and 385 (38%) of patients starting on the individual TCA were receiving some type of antidepressant therapy at 6-8 months, with no significant difference (p = 0.6) in the proportions that had changed to another antidepressant.

CONCLUSIONS

In 2000, only 40% of patients started on an antidepressant continued to be prescribed some antidepressant therapy 6-8 months later. Patients were more likely to continue on SSRIs as a class than on TCAs and the difference in continuation between these two classes occurred within the first 2 months of therapy. However, patients starting on an individual SSRI or TCA were equally likely to change to another antidepressant.

Use of antidepressants by general practitioners and psychiatrists in Australia

OBJECTIVE

To examine the antidepressant prescribing patterns of psychiatrists and general practitioners (GPs) in Australia, focusing specifically on: the prescribed daily dose, the relative proportions (from subsidized dispensing data) of prescriptions written, and how these proportions change over time for a newly listed antidepressant drug (using paroxetine as an example).

METHOD

Retrospective analyses of subsidized claims data (comprising nearly 90% of the community supply of antidepressants) and prescriber surveys.

RESULTS

General practitioners prescribe 86% of subsidized antidepressants in Australia. Almost three-quarters of the antidepressant prescriptions prescribed in primary care management are also initiated by a GP. Psychiatrists prescribed higher doses than general practitioners for all the antidepressants examined. For paroxetine, a higher than average proportion of scripts were written by psychiatrists when the drug was initially available and it only reached the GP/psychiatrist split seen with an established drug in the same therapeutic class (fluoxetine) four years after marketing. The most prominent type of depression that GPs believed they were treating was 'chronic mild depression', which contrasts with the subsidized indication for all newer antidepressant classes of 'major depressive disorders'.

CONCLUSIONS

General practitioners are the major providers of treatment for depression in Australia. When writing prescriptions for tricyclic antidepressants GPs use doses lower than those recommended for major depression, however, most management in primary care is not for conditions regarded by the GP as major depression. A significant number of prescriptions for the newer antidepressants may not accord with the Pharmaceutical Benefits Scheme (PBS) restrictions for use.