Aggressive behaviour in an acute general adult psychiatric unit

AIMS AND METHOD

The study aimed to identify the correlates of aggressive behaviourin an adult acute psychiatric ward. Over a period of 9 months,all incidents of verbal and physical aggressive behaviour exhibitedby in-patients were routinely assessed using the Overt AggressionScale.

RESULTS

Of the 535 patients admitted during the study period, 80 (15%)were involved in a total of 124 aggressive incidents. Of these80, 44 (55%) had a history of previous violence and 54 (68%)had a history of substance misuse. The majority of events occurredearly in the hospital stay and in most cases aggression wasagainst staff.There were significant differences between aggressiveand non-aggressive patients in terms of gender and ethnicity,with the lowest rate occurring in European females.

CLINICAL IMPLICATIONS

These results reinforce clinical impressions, and empiricalevidence, and allow risk assessment to be performed with greaterconfidence. The relevance of ethnicity (or more likely culture)highlights the difficulties of a ‘one size fits all’approachto risk assessment.

Introduction

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Introduction

Aggressive incidents in psychiatric hospitals are frequent andmay be increasing (Fottrell, 1980; Haller & Deluty 1988; James et al, 1990; Atakan, 1995). Previous research has yieldedinconsistent and/or conflicting results but demographic andclinical variables, such as age, ethnicity, gender, diagnosis, psychopathology and ward environment, have been implicated (Shah et al 1991; Davis 1991; Crighton, 1995). The purposeof the present study was to examine prospectively the demographicand clinical variables associated with aggressive behaviourof in-patients in a general adult psychiatric unit servinga catchment area that comprises both urban and rural communitiesand distinguishable cultural/ethnic groups.

Method

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Method

For 9 months, all incidents of verbal and physical aggressivebehaviour exhibited by patients in a 54-bed, adult acute psychiatricunit were assessed and rated routinely on the Overt AggressionScale (OAS; Yudofsky et al, 1986). Incidents were assessedby one of a small group of clinical staff who underwent a singletraining session. Each completed research form was discussedwith the first author. The unit serves a population of 340 000, of which about 21% are ethnic Maori. Details of the servicestructure and functioning have been published elsewhere (Mellsop et al, 2000).Thereare two general adult acute admission wards and an intensivecare ward. The acute wards are staffed by a maximum of 19, 15,and 11 nurses during the day, evening and night shifts respectively.Nursing staff work 8-h shifts. The ethnic distribution of staffapproximates that of the catchment population rather than ofthe patient population, with a male/female ratio of 1:4. Thenumbers of nursing staff vary according to bed occupancy. TheOAS measures verbal and physical aggression including aggressionagainst objects, self and other people. Information on patients’ characteristics, ICD–10 diagnoses (World Health Organization, 1992)and details of each aggressive incident were obtained. All patientsadmitted over the same period who did not exhibit any aggressive behaviour provided the comparison group. Drug screening wasnot routine but was carried out when the treating psychiatristconsidered it indicated.

Data were analysed using ${chi}$ ² and t-tests for group comparisons.

Results

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Results

Of the 535 patients admitted during the study period, 80 (15%)were involved in a total of 124 aggressive incidents. The demographicand clinical characteristics of patients are presented in Table 1.Of the 80, 44 (55%) had a history of previous violence and54 (68%) had a history of substance misuse; 23% of admittedmales but only 7% of females were aggressive at least once.Overall, 20% of Maori patients, 21% of the other non-Europeanpatients and only 11% of European patients exhibited aggressivebehaviour. These differences were statistically significant.Schizophrenia accounted for 48%, bipolar affective disorder27% and substance misuse (all with positive urine tests forcannabis) 14% of the total number of aggressive patients. About30% of patients in each of the schizophrenia, bipolar and substancemisuse categories were aggressive, and fewer than 10% in otherdiagnostic categories.

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Table 1. Demographic and clinical characteristics of patients admitted during the study period

Of the aggressive events, 59 (48%) involved patients with ahistory of violence and 83 (67%) involved patients with a historyof alcohol or drug misuse. Table 2 summarises characteristicsof aggressive events. Of the aggressive episodes, 40 (32%) occurredon the first day of admission and 83 (67%) in the first week;52% took place during the evening shift and 27% and 21% duringday and night shifts respectively. The majority (74%) of patientswere involved in only one incident. Verbal aggression was themost frequent (57% involving nursing staff and 6% involvingother patients). Physical aggression against staff accounted for at least 25% of the events and 15% of all aggressive eventswere rated as moderate-to-severe (OAS score >5). Patientswho exhibited aggressive behaviour had a significantly longertotal length of stay (median 14 days) than the nonaggressivepatients (median 7 days).

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Table 2. Characteristics of aggressive events

All of the aggressive patients were secluded at some point.Physical restraint by nursing staff was required in about athird of the events. The immediate administration of additionalmedication in the form of as required neuroleptics either orallyor intramuscularly was used in about two-thirds of the aggressiveevents. There was no difference in mean OAS score between eventsinvolving patients who did and did not have a history of drugor alcohol misuse (t=1.64, d.f.=122, P>0.1). However, there was a statistically significant difference (t=–4.14,d.f.=122, P<0.01) between the groups in terms of historyof violence, with events involving patients having a historyof violence having a higher mean OAS score than events involvingpatients with no such history.

There was no relationship between ethnicity and history of violencefor non-European patients ( ${chi}$ ²=0.067, d.f.=1, P>0.1). However,there was a relationship between ethnicity and a previous historyof drug or alcohol misuse, with Maori patients more likely(80%) to have such a history than European patients (51%; ${chi}$ ²=6.492,d.f.=1, P<0.05).

Discussion

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Discussion

This study provides further information about the correlatesof aggressive behaviour in a general adult psychiatric unitin New Zealand. Although generalisation of the results shouldbe undertaken with caution, the study provides the first publishedinformation on these specific issues. The association of violencewith male gender is well recognised (Davis, 1991; Shah et al, 1991).

The finding that Maori and other non-European patients weremore likely to be involved in aggressive incidents is interesting.It may reflect more severe psychopathology in this group ofpatients, which in turn may reflect cultural differences inservice access, service utilisation or real differences in phenomenology.A higher proportion of Maori patients had a history of substancemisuse, which may be another significant factor. Previous studies have suggested that aggressive behaviour in inpatient unitsoften involves patients with schizophrenia and bipolar disorders (Tardiff, 1999), particularly those who are acutely psychoticor manic. Similarly, in our study, patients with schizophrenia,mania and those with substance misuse were most frequently involvedin aggressive events. There is evidence for an increase in substance-relatedpsychotic disorders over time (Cantwell et al, 1999), it istherefore not surprising that 7% of our total sample were inthat category. As the study recorded only the single, codedprimary clinical diagnosis, comorbidity could not be considered.Our finding that nearly 70% of the aggressive episodes tookplace within the first week of admission is consistent withthe view that stage or phase of illness, in terms of acuityor remission, is a useful predictor of violence (Davis, 1991),especially in the short term. Acutely ill patients are particularlyvulnerable and may feel provoked or intimidated, especiallyif they are psychotic and admitted involuntarily. All of ourpatients who were involved in aggressive events were compulsorilydetained. This is probably a reflection of the use of risk and violence as criteria for compulsory admission. The findingthat most patients exhibiting aggressive behaviour were likelyto be secluded is consistent with several studies (James et al, 1990;El-Badri & Mellsop 2002).

There is a consensus that a history of aggressive behaviouris the best predictor of future violence (Davis, 1991; Shah et al, 1991;Crighton, 1995). In our study, 55% of patients who were aggressivehad a history of previous violence and nearly 70% had a historyof alcohol or drug misuse. Substance misuse among psychiatricpatients has consistently been shown to be a significant riskfactor for aggression and disturbed behaviour (Soyka, 2000).In our sample, 54 aggressive patients (68%) had a history ofalcohol or drug misuse. Substance misuse probably exacerbatespsychotic symptoms and/or interacts with personality and othersocial variables and treatment nonadherence (Soyka, 2000).In our study, over half of the aggressive events occurred inthe evening and in most cases were directed against the nursingstaff. Threats of violence and verbal aggression predominated,with serious physical aggression being less common. In theevening, however, aggressive episodes peaked at certain times.The first peak coincided with the change of shift and medicationtime (4–6 p.m.) and the second with bedtime (10 p.m.);these are times at which hospital rules are enforced. Settinglimits on patient behaviour and attempting to accomplish specifictasks (including the administration of medication) have beennoted to provoke aggressive behaviour (Sheridan et al, 1990;Tardiff, 1992; Lance et al, 1995). Furthermore, the skillof staff and their training in limit-setting and aggressioncontrol technique are equally important (Infantino & Musingo 1985). Staff skills, their attitude and experience, and staff–patient interactions are interrelated. These issues and the impactof the way hospital rules/regimes are enforced require furtherexamination.

The usage of seclusion in New Zealand may be a practice awaitingan evidential base or a change in service culture.

In this unit, the average admission rate was 4 patients perday and the average bed occupancy was 84% during the studyperiod. We did not find any significant relationship betweenaggressive episodes and bed occupancy or admission rates.

References

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