Ethnicity and quality of antipsychotic prescribing among in-patients in south London

Ethnicity may influence treatment decisions in mental disorders.We undertook a survey of the prescribing of antipsychoticsfor in-patients in three south London mental health trusts.A total of 255 patients (152 White, 103 Black) were included.Median dose of antipsychotic (% of licensed dose) was 58.3%for White and 50.0% for Black patients (adjusted effect size=0.14, 95% CI –0.34 to 0.63). High-dose antipsychotics wereprescribed to 15.1% of White and 11.7% of Black patients (adjustedodds ratio (OR)=0.5, 95% CI 0.19–1.33), and antipsychoticpolypharmacy was recorded for 25.7% and 31.1% respectively(adjusted OR=3.05, 95% CI 1.44–6.46). Prescribing qualitywas similar for Black and White patients.

INTRODUCTION

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INTRODUCTION

There have been suggestions of institutional racism in UK mentalhealth services.¹ Several, mainly American, studies indicatethat Black patients are more likely than White patients toreceive high doses of antipsychotics and depot formulations^2–4 and less likely to be treated with atypical antipsychotics.⁵ Many of the studies are limited by the failure to collect andcorrect for other factors likely to affect prescribing practice.We published a single-centre study⁶ of antipsychotic prescribingwhich took into account over 20 potentially confounding factors,but found no difference in corrected odds of receiving highdoses of antipsychotics or antipsychotic polypharmacy. We wantedto know whether our results would differ in a larger studywith greater power to detect smaller differences and whichincluded participants from other trusts.

Method

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Method

This study was conducted at the South London and Maudsley, SouthWest London and St George’s, and Oxleas National HealthService (NHS) Trusts during late 2006 and early 2007. We soughtand obtained individual approvals for the study through localclinical audit channels.

Patients included were in-patients, designated Black or White,and prescribed and taking one or more regular antipsychotics.Patients were classed as Black if both parents were also Black(that is, Africans, African Americans and African–Caribbeans).Mixed-race patients were excluded. All suitable patients onall acute general psychiatry wards in every hospital withineach trust were approached over a 3-month period in 2006/2007:none was excluded except for the reason above. The outcomesof dose (expressed as a percentage of licensed maximum),⁷being prescribed antipsychotic medication above maximum dose,polypharmacy and costs were determined by reference to eachpatient’s medication chart and to standard referencetexts for dose⁸ and cost.⁹

Potential confounding factors (23 in total) were predeterminedand details were obtained from case notes, self-report, orby measurement or calculation and confirmed by nursing or medicalstaff where appropriate. Clinical Global Impression–Severity¹⁰ (CGI–S) was rated on the day of data collection (nurseor medical staff assessment).

A sample size of 298 was calculated to be required to give an80% chance of detecting a 5% absolute difference for our mainoutcome (dose) ( ${alpha}$ =0.05, ${rho}$ =0.8). We aimed to compare four outcomes(dose, rate of polypharmacy, high-dose prescribing and useof atypical antipsychotics) between our two groups and to adjustcomparisons for the effect of confounding (predictive) variables.For the outcome of dose we used a linear regression model to provide an estimate of unadjusted effect of ethnicity on dose.Potential confounding variables were then tested to identifypredictive factors (significance level of P<0.1). Predictivefactors were then included in a rerun regression model, producingadjusted effect size for ethnicity. Transformations were usedwhen necessary. A similar approach was used for the binaryoutcomes of high dose, polypharmacy and prescribing of atypicaldrugs, but with logistic regression modelling used.

Results

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Results

We approached 300 patients and 255 gave informal informed consentto be interviewed. Of the 45 patients who declined to takepart, 21 (46.7%) were Black, 23 (51.1%) were male and the meanage was 41.7 years. Details of included patients are givenin the online Table DS1.

Median dose was 58.3% for White patients and 50.0% for Blackpatients (adjusted effect size=0.14, 95% CI –0.34 to0.63; P=0.56). High-dose antipsychotics (>100% licensedmaximum) were prescribed to 15.1% of White and 11.7% of Blackpatients (adjusted OR=0.5, 95% CI 0.19–1.33; P=0.16)and polypharmacy to 25.7% and 31.1% respectively (adjusted OR=3.05,95% CI 1.44–6.46; P=0.004). With polypharmacy, the adjustedodds ratio was largely driven by centre differences: one centre showed an exceptionally high rate of polypharmacy in Blackpatients (74% v. 37% in White patients; other centres: 13%v. 17% and 16% v. 10% respectively). There was no differencein the prescribing of atypical antipsychotics (White 77.6%,Black 68.9%: adjusted OR=0.57, 95% CI 0.21–1.5; P=0.25).

Discussion

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Discussion

In this study, ethnicity was not significantly associated withdose of antipsychotic, the prescribing of high-dose antipsychoticsor the use of atypical antipsychotics. Prescribing qualitywas thus no worse for Black patients than for White patients.Only the outcome of adjusted odds ratio for antipsychotic polypharmacyshowed any association with ethnicity. This is an importantobservation but it should be noted that absolute rates of polypharmacydiffered markedly in only one centre and the overall difference in prevalence was small (25.7% for White v. 31.1% for Black patients).

Our findings are therefore in some contrast to studies whichsuggest a higher likelihood of higher-dose prescribing in Black patients^2–5 and a lower use of atypical drugs.⁵ Thismay reflect true differences in practice at different times(there is evidence of ethnic differences in prescribing inthe 1990s in south London)¹¹ or in different locations (manyof the studies^3–5 examine US prescribing) but may alsobe linked to the relatively limited extent of adjustment forconfounding variables in previous studies. Adjustment for theseconfounders is essential to the process of establishing or otherwise ethnicity as having an association with prescribing quality.

There were several limitations in our study design. We did notmeet our recruitment target of 298 patients, although confidenceintervals ultimately excluded major differences in outcome,particularly with respect to a possibility of a lower qualityof prescribing for Black people. In addition, some of our datacollection relied on patient self-report – a notoriouslyunreliable source, especially, perhaps, in psychiatric in-patients.Also, our assessment of clinic status was approximate (usingthe CGI–S scale) and may not of have been relevant topatients’ condition at the time of the initial prescription.Lastly, our sample was exclusively in-patients and so our resultsmay not generalise to the majority of patients now treatedin the community.

Notwithstanding these limitations, it is reasonable to concludethat in this study prescribing quality did not differ substantiallybetween Black and White patients. Black patients were not prescribedhigher doses than White patients. Black patients are more likelyto receive antipsychotic polypharmacy, but this differencewas only noticeably higher in one centre. Black patients werejust as likely as White patients to receive atypical antipsychotics.

ACKNOWLEDGMENTS

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ACKNOWLEDGMENTS

We thank Andrew Fuller, Deirdre McArdle, Laraine James, SarahJones and Vanessa Jones for data collection, and Sabine Landauand Manoharan Andiappan for statistical analysis. This studywas funded by Trustees of the South London and Maudsley NHSFoundation Trust.

REFERENCES

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