Factors Predicting the Use
`of Multiple Psychotropic Medications
`
`Michael B. Nichol, Ph.D., Glen L. Stimmel, Pharm.D.,
`and Sult C. Lange, Pharm.D., M.P.H.
`
`Background: Recent studies have ques-
`tioned the appropriateness of some types of
`psychotropic medication prescribing, especially
`by general practitioners. The purpose of this
`study is to investigate factors that predict
`prescribing of multiple psychotropic medica-
`tions. a class that may represent more
`complicated cases.
`Method: This study analyzed data from the
`I989 National Ambulatory Medical Care
`Survey (NAMCS}. Multiple logistic regression
`methods were used to determine variables that
`
`predicted the provision or ordering of multiple
`psychotropic medications during a single office
`visit.
`
`Results: Patients who visited psychiatrists
`were six times more likely to receive psycho-
`tropics in combination than patients visiting
`general practitioners. Patients diagnosed as
`manic were four times more likely to receive
`multiple psychotropics. and those diagnosed as
`schizophrenic were three times more likely.
`Patients visiting physicians in the Northeast
`and South were significantly less likely to
`receive psychotropics in combination than
`patients in the Midwest.
`Conclusion: Although general practice
`physicians contribute to the use of multiple
`psychotropic medications. patients visiting
`psychiatric specialists are much more likely to
`be provided combination therapy.
`(J Clin Psychiatry l995.'56:60—66)
`
`Received April 6, l 993.‘ accepted May l2. l993. From the School
`of Pltorrnocy {Drs. Nichol. Stintmel. and Lattge). the Andrus School of
`Gerontology ( Dr. Nichol). the School of Me-dt'ct'ne (Dr. StimmelJ. and
`the University Hospital {Dr. Lange). University of Southern California,
`Los tingeies.
`Portions of these data have been presented at the l20th annual
`meeting of the American Public Health Association. Washington. D.C..
`November i992.
`Reprint requests to: Michael B. Nichol. Ph.D.. Department of
`Pharmaceutical Economics and Policy. USC School of Pharmacy.
`CHP—l40F. l540 East Alcazar Street. Los Angeles. CA 90033.
`
`J Clin Psychiatry 56:2, February 1995
`
`A number of health care researchers have noted
`
`that some psychotropic medication prescribing
`appears to be suboptimal, especially with regard to
`prescribing by primary care physicians.” The limited
`data presently available indicate that prescribers rarely
`note appropriate psychiatric diagnoses in conjunction
`with psychotropic use? and that medications used
`within particular categories (such as antidepressants)
`may have side effect profiles that negatively affect pa-
`tient outcome.‘ Several authors have noted that pri-
`mary care physicians represent a significant portion of
`the mental health network and prescribe the majority
`of psychotropic medications.“ although they may not
`have extensive training in the diagnosis and treatment
`of patients with mental diseases.
`An area of prescribing that has not been investi-
`gated is the simultaneous use of multiple psychotropic
`medications. By definition. patients requiring multiple
`psychotropic medications can be considered compli-
`cated. and the potential for inappropriate therapy is
`high, if only because of the increased likelihood of
`adverse effects and drug interactions. Several problem
`areas may develop as a result of multiple concomitant
`psychotropic use: duplicative effects {two or more
`medications from the same class). offsetting effects
`(two or more medications that have opposite action),
`and lack of therapeutic indication {two or more medi-
`cations in which there is inappropriate use). Multiple
`psychotropic prescribing with these characteristics has
`the potential to create significant negative patient out-
`comes.
`
`There is increasing interest in the special problems
`of patients with co-occurring disorders.” The lack of
`attention to multiple psychotropic prescribing is un-
`derstandable since it occurs relatively infrequently and
`few data sources provide sufficient detail regarding
`drug use and diagnosis to determine inappropriate use
`categorically. However. concomitant use of psycho-
`tropics provides a distinct opportunity to identify phy-
`sician and patient characteristics that may account for
`this lack of attention, especially insofar as it might be
`possible to determine whether primary care physicians
`contribute disproportionately to problem prescribing.
`The purpose of this research is threefold: to identify
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`the prevalence of multiple psychotropic prescribing by
`drug category, to classify potential inappropriate or
`questionable prescribing of multiple psychotropics.
`and to determine which factors predict multiple psy-
`chotropic prescribing behavior.
`
`CONCEPTUAL BACKGROUND
`
`One model that has been used extensively to predict
`the use of health services is that proposed by
`Andersen‘ and expanded by Andersen and Newman“ in
`which health care decision making is hypothesized to
`be affected by four sets of variables: predisposing, en-
`abling. need, and health services characteristics. Pre-
`disposing characteristics include such issues as family
`composition, social structure, and health beliefs. The
`enabling category includes family and community re-
`sources. The need category incorporates concepts of
`illness and patient response. This model has been em-
`ployed to explain prescription and over-the-counter
`drug use""" and a variety of other health services.”
`The I989 National Ambulatory Medical Care Sur-
`vey (NAMCS) provides data on each of these four di-
`mensions. For
`the purposes of this study.
`the
`predisposing factors included patient age, gender. and
`ethnicity. Patient age has been shown to be associated
`with increasing use of medications in a variety of stud-
`ies.”"‘ Women have been shown to be more likely to
`use prescriptions" and are more likely to be prescribed
`psychotropic medications."“” Several authors”“" have
`included ethnicity variables as covariates in studies of
`psychotropic medication use. but their results were
`conflicting. Therefore. the impact of ethnicity could
`not be predicted.
`Enabling variables encompassed the specialty of the
`physician and the type of health insurance coverage
`used to pay for the patient visit. Physician specialty
`could be expected to be a good predictor of multiple
`psychotropic prescribing because more complicated
`mental health cases that may require multiple medica-
`tions are likeiy to be supervised by psychiatrists. Evi-
`dence from the i985 NAMCS established that
`
`psychiatrists prescribed multiple psychotropics more
`frequently than physicians in other specialties.’ It can
`be expected that health maintenance organization
`(HMO) patients may receive less intensive care than
`those whose care is financed through fee-for-service
`insurance plans.” although treatment outcome appears
`to be comparable." Less intensive care may mean that
`patients are less likely to receive multiple prescrip-
`lions.
`
`Need variables, for the purposes of this model. in-
`clude whether the patient presented a psychiatric com-
`plaint. diagnostic categories
`identified by the
`physician. and whether the appointment was a repeat
`
`61
`
`visit for the same problem. Presence of a psychiatric
`complaint was used as an explanatory variable be-
`cause it represents a clear indication that patient per-
`ception corresponds to prescribed medication. even
`though the complaint may also be expressed in terms
`of a physical manifestation of illness not easily con-
`nected to mental diagnoses.m" Diagnosis identified
`by the physician could be expected to be a strong pre-
`dictor of drug prescribing. except for the fact that ex-
`isting studies indicate that primary care physicians
`may not recognize psychiatric disorders’ or may be re-
`luctant to identify mental health diagnoses.’ The fact
`that the physician had previously treated the patient
`for a similar condition may be correlated with the use
`of multiple psychotropics. since a second visit for the
`same diagnosis could imply that the condition may be
`chronic or complicated.
`Two variables were used to measure health system
`characteristics: region of the country and the provision
`of psychotherapy services. Extensive research tins
`shown that health care service utilization varies dra-
`
`matically throughout the United States.” Wells et al.“
`used Health Insurance Experiment data to show that
`residents living in sites in western and eastern states
`were more likely to visit mental health specialists than
`those in midwestern sites, and midwestern residents
`were more likely to visit a mental health specialist
`than their contemporaries in the South. In the multiva-
`riate analyses that follow, patients residing in
`midwestern states are the comparison group.
`The impact of psychotherapy on multiple psycho-
`tropic prescribing was unclear. a priori. Patients who
`receive psychotherapy could be expected to be more
`likely to suffer from complicated conditions in which
`multiple psychotropic medications may be used". On
`the other hand. these patients may be more involved
`in treatment and less likely to use multiple drugs, de-
`pending on the training of the caregiver and the diag-
`nosis.
`
`METHOD
`
`The NAMCS is conducted periodically by the Na-
`tional Center for Health Statistics (NCI-lS).15 The 1989
`survey included information regarding 38.384 patient
`visits representing estimates of 692 million visits to
`physicians throughout the United States. Seventy-four
`percent of the eligible physicians who were contacted
`(N = 142!) participated in the survey. Sample counties
`were stratified by size. region, and patient demo-
`graphic characteristics, while the physicians sampled
`within counties were stratified by specialty and prac-
`tice size.
`
`For the purposes of this study. all visits of patients
`18 years of age and older in which a psychotropic
`
`J Clin Psychiatry 56:2, February 1995
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`Multiple Psychotropic Prescribing
`
`Table 1. Total Psychotropic Medication Prescribing and Proportion Involving Multiple Psychotropics for Patients Older
`Than 18 Years of Age
`
`Total Visits
`Category
`Involving Dnig
`i2.03|.94U
`Antidepressant
`Stimulant
`395.8I0"*
`2.544.084
`Antipsychotic
`Anorectic
`|.003.759
`2.240.739
`Anticholinergic
`Barbiturate
`6l4.B85
`l0.930.630
`Berlzodiazepine
`L724. I35
`Anxiolytic
`Lithium
`|.340.l93
`2.70l.6l5
`Hypnotic
`35.577790
`Total
`"Unstable estimate. standard error > 30%.
`
`% All Office
`Visits
`1.74
`.06
`.37
`.|4
`.32
`.09
`[.53
`.25
`.|9
`.39
`5.|3
`
`Visits With Single
`Drug in Category
`8.568.899
`207.429
`I. I 87.937
`846.02!
`l.676.834
`598.924
`8.52l.322
`|.487.087
`383.I23
`I .768.6I0
`25.246.I86
`
`Visits Involving
`Multiple Prescribing
`3.5|3.04|
`|88.38|'
`l.356.l47
`l57.738'
`563.905
`l5.96l“
`2.409.308
`237.048‘
`957.070
`933.005
`l0.33l.6€l4
`
`% Visits within
`Category With
`Multiple Prescribing
`29.|
`47.6
`53.3
`l5.7
`25.2
`2.6
`22.0
`I 3.7
`7 I .4
`34.5
`29.0
`
`medication was prescribed were abstracted for analy-
`sis. Medications were categorized according to the
`American Society of Hospital Pharmacists‘ drug clas-
`sification scheme.” Two medications (both combining
`amitriptyline and perphenazine) were included in this
`study as combination products. ICD-9-CM (Interna-
`tional Classification of Diseases. Ninth Revision.
`
`Clinical Modification) diagnoses were compiled into
`the same categories used by Hohmann et al.' Physi-
`cian specialty was aggregated into three classes: gen-
`eral practice {general practice. family practice. and
`internal medicine). psychiatric specialty, and other (all
`other specialties).
`The survey method used by NCHS requires the ap-
`plication of sampling weights to generate estimates of
`nationwide patient visits. In the descriptive tables that
`follow. weighted estimates of total visits and percent-
`ages are reported. The extrapolation of national visits
`from a limited sample creates potential problems with
`regard to the confidence level of estimates for rare oc-
`currences. Estimates of national visits that have rela-
`
`tive standard errors exceeding 30% are considered
`unreliable by the NCHS3" and are noted.
`Multiple logistic regression methods were applied
`to the unweighted figures because parameter estimates
`and standard errors are not affected by sampling
`weights.” The categories of predictor variables were
`entered into the model sequentially. with the predis-
`posing variables entered first, followed by enabling,
`need. and health services categories. This “step-up“
`procedure provides an estimate of the relative contri-
`bution of each domain to the probability that the at-
`tending physician ordered or provided multiple
`psychotropics during the patient visit. McFadden‘s
`pseudo-R2 (similar to a log likelihood ratio) was used
`to compare the degree to which these categories im-
`prove predictive power.” Odds ratios and confidence
`intervals were calculated for significant explanatory
`variables using exponentiation.
`
`J Clin Psychiatry 56:2. February 1995
`
`RESULTS
`
`Prevalence of Multiple Psychotropic Prescribing
`Based on the NAMCS. the NCHS estimated that a
`
`total of 692.7 million patient visits occurred during
`I989. As noted in Table 1, approximately 35.6 million
`patient visits involved at least one prescription for a
`psychotropic medication. These data show that certain
`categories of medications are more likely to involve
`multiple psychotropic prescribing. For example,
`lithium. antipsychotics. and stimulants are the most
`likely psychotropics to be used in combination with
`other psychotropics. It is important to note that medi-
`cations in these three categories are infrequently pre-
`scribed, as the total use of all three constituted less
`
`than 1% of all office visits during 1939 (0.62%). The
`most frequent psychotropic medication combinations
`include antidepressants: benzodiazepines and antide-
`pressants (24.5% of all combined psychotropics). anti-
`psychotics and antidepressants (17.0%). and lithium
`and antidepressants (8.3%). Several other combina-
`tions are worthy of note. although the relatively small
`number of visits yields unreliable estimates: hypnotics
`and antidepressants (6.1%). antipsychotics and lithium
`(5.1%). and antipsychotics and anticholinergics
`(5.0%). An estimated 402,000 patient visits during
`1989 involved the provision or ordering of two psy-
`chotropic medications within the same class.
`
`Potentially Problematic Prescribing
`Potentially problematic combinations could include
`duplicative therapy. offsetting therapy. or therapy in
`which there are no clinically accepted indications. Us-
`ing this definition. nearly 2.8 million (27%) of the
`l0.3 million visits in which multiple psychotropic
`medications were prescribed occurred in combinations
`that could be considered therapeutically questionable.
`Among the many combinations of psychotropic
`drugs represented in this sample. three appear with
`
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`Table 2. Legit Estimates of the Use of Multiple Psychotropic Medications*
`
`Estimate
`
`0 Estimate
`
`B Estimate
`
`Estimate
`
`Odds
`Ratio
`
`Confidence
`Interval
`
`—.014"
`—.0l9
`-.l35
`
`(16.29)
`(.02)
`(1.02)
`
`-0006
`. 104
`-.25
`
`(.01)
`{.54}
`(1.52)
`
`.022
`2.06‘
`-009
`—.0l2
`J82
`
`(.01)
`(l6'?.'l'2)
`(.O0|)
`(.003)
`I .152)
`
`-.000]
`.063
`-322
`
`(.0007)
`(.22)
`(2.23)
`
`.147
`L461’
`.056
`-.00’.-'
`.213
`
`.303
`.241
`.337
`.471”
`.912”
`1.14“
`.32
`.53
`.222
`
`(.55)
`(52.36)
`(.04)
`L001}
`(.37)
`
`(3.03)
`(1.57)
`(.63)
`to.) 1)
`(3.44)
`(13.54)
`(1.12)
`(1.74)
`(.63)
`
`3.417, ll.Sl
`
`1.02. 2,07
`
`L06. 2.26
`1.60. 5.62
`2.20. 7.71
`
`-.000
`.07l
`-305
`
`(.000)
`(.24)
`(I734)
`
`(.75)
`.173
`1.344" (36.37)
`-.0215
`(.009)
`.043
`(.04)
`.114
`(.23)
`
`(4.32}
`(2.76)
`(.4?)
`(5.00)
`(I l.'i2)
`([960)
`(L44)
`(2.95)
`(1.29)
`
`(2.83)
`(2 L09)
`(7. I0]
`(2.48)
`
`.375‘
`.322
`.301
`.434‘
`1.10‘
`1.42“
`.30‘:
`.11
`.32
`
`—.49
`—.9s*
`_.4s'-'
`—.33
`311.35"
`.l't"6
`
`Variable
`Predisposing
`Age
`Seat (1 = female)
`Race (1 = minority)
`Enabling
`Other physician specialty
`Psychiatric specialty
`HMO payment source
`Medicare payment source
`Medicaid payment source
`Need
`Psychiatric complaint
`Neurologic diagnosis
`Stress diagnosis
`Depression diagnosis
`Schizophrenia diagnosis
`Mania diagnosis
`Other psychoses diagnosis
`Other psychiatric diagnosis
`Repeat visit
`Health services
`Psychotherapy provided
`Northeastern region
`Southern region
`Western region
`Model 13
`Pseudo-R2
`‘Numbers in parentheses beside parameter estimates represent Wald chi—square estimates. The number of visits in the sample equals 2085.
`"p<.00l. "p-:.0l. “p<.05.
`
`I 7.56“
`.0099
`
`260.19“
`.147 '
`
`235.30"
`.lb|
`
`sufficient frequency to merit concern: antidepressant
`and antipsychotic combinations: multiple concomitant
`central nervous system (CNS) depressants (including
`barbiturates. benzodiazepines. anxiolytics. and hyp-
`notics): and CNS-stimutant!CNS-depressant combina-
`tions. Of the more than 12 million visits involving
`antidepressant drugs. almost 1.3 million (10.7%) also
`received an antipsychotic. Approximately 65% of this
`combination was prescribed by psychiatrists and virtu-
`ally all of these were repeat visits for previously
`diagnosed problems. Psychotherapy services were pro-
`vided during 64.0% of these visits.
`A total of 639.580 visits involved multiple CNS
`depressants in 1989. Although this constituted less
`than 2% of all psychotropic visits, these combinations
`are notable. For example. while only about 4.3% of
`patients receiving a benzodiazepine also received a
`hypnotic drug, such a combination is rarely necessary.
`Less than 30% of this use occurred during visits to
`psychiatric specialists.
`There was sufficient frequency of the combination
`of stimulanttlanxiolytic, CNS depressantfstimulant. and
`anorecticfbenzodiazepine to deserve mention, even
`though the low number of visits renders the estimates
`unreliable. It is notable that most of these combina-
`
`tions were prescribed by nonpsychiatrists, with the ex-
`ception of the CNS depressantistimulant category.
`
`Fortunately, very few visits included CNS depressant!
`stimulant combinations (less than 94.000. or less than
`
`0.3% of all visits involving psychotropics).
`Nearly 54% of the potentially problematic combi-
`nations were prescribed by psychiatric specialties,
`while 32.0% were prescribed by general practice spe-
`cialties. Approximately 58% of the questionable pre-
`scribing by psychiatrists was represented by the
`antidepressantfantipsychotic combination. Primary
`care physicians prescribed 47.0% of the combinations
`involving two or more medications within the same
`class (e.g.. two antidepressants).
`
`Factors Predicting Multiple Use
`The multivariate analysis provides estimates of the
`factors that predict multiple psychotropic prescribing.
`The results in Table 2 show the strongest effects in
`the enabling. need. and health services categories.
`Variables within the predisposing category (age. sex.
`and race) did not predict the use of multiple psycho-
`tropic medications. The greatest
`increase in the
`pseudo-R3 statistics occurred when the enabling char-
`acteristics were entered into the model.
`
`Enabling. Psychiatric specialty was the only en-
`abling variable to provide predictive power. As de-
`noted by the odds ratios, this variable was the single
`strongest predictor of multiple psychotropic use. Spe-
`
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`cifically. patients who visit a psychiatrist were greater
`than six times more likely to receive an order for mul-
`tiple psychotropic medications than patients who visit
`a general practice physician. Payment source did not
`prove to be a significant predictor of multiple use.
`Need. Several variables in the need category dem-
`onstrated predictive power. although the category as a
`whole made only a modest contribution to the model's
`overall predictive power (an increase of less than 2%
`in the pseudo-R2 statistic). The diagnostic classes were
`the best predictors in this category. Visits in which the
`physician identified a mania diagnosis were four times
`more likely to result in multiple psychotropic orders
`than visits in which a non-psychiatric diagnosis was
`specified. Visits with schizophrenia diagnoses were
`three times more likely than visits with only non-psy-
`chiatric diagnoses to result in the ordering of multiple
`psychotropic medications. Visits including depression
`diagnoses were approximately one and a half times
`more likely to result in such orders.
`Health services. Regional differences provided the
`greatest predictive power in the health services cat-
`egory. As noted in Table 2. visits occurring in the
`northeastern and southern regions of the United States
`were much less likely to receive orders for multiple
`psychotropic medications than patients
`in the
`midwestern part of the country. Interestingly. visits in
`which psychotherapy was provided were not more
`likely to result in the prescribing of multiple psycho-
`tropics.
`
`DISCUSSION
`
`These results confirm previous studies that showed
`that psychiatric specialties are responsible for the ma-
`jority of the multiple psychotropic prescribing.‘ Thus.
`it appears that primary care physicians and other non-
`psychiatrists either refer patients who present compli-
`cated psychiatric profiles to specialists. may not
`recognize the more complex diagnostic issues. or sim-
`ply do not use multiple psychotropics to treat such pa-
`tients. The small proportion of multiple psychotropic
`medication visits to nonpsychiatrists provides prelimi-
`nary evidence that these physicians may recognize the
`difficulties associated with treating more complicated
`psychiatric cases.
`The relatively low incidence of multiple psycho-
`tropic prescribing within individual categories should
`be cause for some celebration. but there is cause for
`
`concern. as well. Nearly 40% of all multiple psycho-
`tropic prescribing reported in the NAMCS data oc-
`curred in categories with no readily apparent clinical
`justification. The results addressing the three poten-
`tially problematic categories (antidepressant and antip-
`sychotic; multiple concomitant CNS depressants: and
`
`J Clin Psychiatry 56:2. February 1995
`
`Multiple Psychotropic Prescribing
`
`CNS depressant and stimulant combinations) deserve
`particular mention. These combinations are particu-
`larly worrisome because of the lack of clinical support
`for their frequent use.
`While there are several indications for the combi-
`
`nation of an antipsychotic drug with an antidepressant.
`these indications are infrequent. Schizophrenic pa-
`tients. who require chronic antipsychotic drug therapy,
`may at times experience major depressive episodes
`necessitating drug treatment.” Also. patients with a
`major depressive disorder may infrequently experi-
`ence psychotic symptoms.” Psychotic depression must
`often be treated acutely with both an antidepressant
`drug and an antipsychotic drug, but there is no evi-
`dence to support a role for antipsychotic drug therapy
`in nonpsychotic depression." It is impossible in this
`study to determine whether the nearly I 1% of patients
`receiving an antidepressant and antipsychotic drug
`meet one of these two conditions. However. the com-
`
`bination of antidepressant and antipsychotic is often
`used for either anxious nonpsychotic depression or for
`an inadequately diagnosed patient where drug therapy
`is being used as a diagnostic tool. Both situations are
`problematic. Use of an antipsychotic drug for anxiety
`or agitation that accompanies depression is rarely ap-
`propriate when safer and more effective antianxiety
`drugs can be used. Use of an antipsychotic drug.
`merely for its sedative effect and the risk of tardive
`dyskinesia. in a patient without psychotic symptoms is
`of even greater concern than the lack of any docu-
`mented evidence of benefit. Diagnostic uncertainty
`also accounts for some of the use of combination psy-
`chotropic drugs. However. success or failure of com-
`bination therapy does not help clarify the diagnosis as
`would use of a single drug trial.
`The primary concern regarding the combination of
`CNS depressants is unnecessary drug duplication. At
`best. the use of multiple CNS depressants represents
`unnecessary use of additional drugs. Selection of an
`antianxiety drug should include consideration of de-
`sired onset of effect. elimination half-life. and a dose
`
`and dosage schedule that matches the symptoms and
`needs of the patient. It is rarely necessary to prescribe
`one antianxiety drug for the daytime and another drug
`for sleep at night. It is also rarely necessary to use
`two benzodiazepines or two anxiolytic drugs together
`except during a transition from one to another.” For
`some patients. however. multiple CNS depressants
`pose the risk of serious adverse effects such as exces-
`sive sedation. impaired psychomotor performance.
`ataxia. and possible falls.”""
`The multivariate results provide strong evidence
`that multiple psychotropic use is related to psychiatric
`specialty. This fact. combined with the descriptive
`data showing that patients in the antidepressant.’anti-
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`psychotic combination category generally receive
`psychotherapy and are uniformly repeat patients, indi-
`cates that psychiatrists may be caring for more com-
`plicated patients who may require unusual therapeutic
`regimens. At the least. the multivariate results illus-
`trate that primary care physicians avoid the more
`complicated cases that require psychotropic combina-
`tions.
`
`The observation about the complexity of these
`cases is further reinforced by the contribution of need
`variables in predicting the use of multiple psycho-
`tropic medications, particularly with regard to the di-
`agnostic categories. Patients who received a diagnosis
`of either mania or schizophrenia were much more
`likely to receive multiple psychotropics. While bipolar
`patients more routinely receive multiple psycho-
`tropics. in schizophrenia it more likely reflects com-
`plexity. This result is consistent with the complexity
`hypothesis because both mania and schizophrenia are
`more likely to require treatment with multiple psycho-
`tropic medications.
`The regional differences apparent in the multivari-
`ate results deserve special mention. Patients in virtu-
`ally all other regions of the country were less likely
`than those in the Midwest to be ordered or provided
`psychotropics in combination, although differences
`between the West and Midwest were not statistically
`significant. These practice variations are not unusual,
`but the consistent direction of the effect indicates that
`
`practitioners in the Midwest may be less aware of the
`problems associated with prescribing multiple psycho-
`tropic drugs.
`The limitations of the NAMCS data mean that
`
`these results should be considered exploratory in na-
`ture. Although a large proportion of all psychotropic
`visits involved multiple drugs. these still represent a
`relatively small number of office visits across the na-
`tion. Thus, estimates derived from the NAMCS data
`
`are subject to significant variability. as evidenced by
`the high relative standard error for some categories.
`In addition to the fact that many of these combina-
`tions represent unstable estimates. the NAMCS data
`set suffers some important limitations that must be
`recognized. First, these data were collected at a single
`point in time, which can result in overrepresentation
`of frequent users.” Second, the data set does not in-
`clude all information that would be useful to deter-
`
`mine problems of multiple psychotropic prescribing.
`For example, it is impossible to determine whether the
`listed medications were added to an existing regimen
`prescribed by another physician. were substitutes for
`existing medications. or were only used for a brief
`time period. Third, physicians could only report a
`maximum of five medications. This limitation may be
`particularly important when analyzing visits to pri-
`
`65
`
`mary care physicians. which may generate prescrip-
`tions for numerous conditions. Fourth. physician re-
`luctance to identify a patient with a mental health
`diagnosis may result in underreporting. Fifth. the sur-
`vey was completed by physicians or office staff with
`no verification of responses.
`Research conducted within the last decade supports
`the use of multiple psychotropic medications in some
`cases. However. future research into co-occurring
`mental disorders should pay particular attention to the
`use of multiple psychotropic medications and the
`problems associated with such use. Population-based
`research ghould document clinical diagnoses. reasons
`for multiple psychotropic use. and the periodicity of
`multiple use (short- or long-term). Particular attention
`should be directed to determining the appropriateness
`of multiple psychotropic prescribing.
`
`Drug names: perphenazinelamitriptyline (Etrafon. Triuvil).
`
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`Alkermes, Ex. 10
`
`6 of 7
`
`Alkermes, Ex. 1071
`
`

`
`Multiple Psychotropic Prescribing
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