An intervention study to prevent weight gain or reduce weight in people with serious mental illness who take second generation antipsychotics

Park, Tanya (2011) An intervention study to prevent weight gain or reduce weight in people with serious mental illness who take second generation antipsychotics. PhD thesis, James Cook University.

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Introduction: Weight gain and obesity has reached epidemic proportions with the prevalence of Metabolic Syndrome (MetS) reaching 20-25% of the global population. MetS is a cluster of metabolic abnormalities, including weight gain, associated with an increased risk of cardiovascular disease, diabetes and stroke. While individuals in the general population are at risk of physical conditions such as MetS, people with mental illness are at even higher risk. The increased incidence of MetS for people with serious mental illness has been linked in part to the use of second generation antipsychotic (SGAs) medication.

Background: Antipsychotic medication has long been associated with physical side effects, including cardiovascular and metabolic effects such as weight gain. The association between weight gain, diabetes and the SGAs is linked to a number of hypotheses including the blocking of the serotonin receptors (5-HT2) by the medication which results in a decreased serotinergic transmission thereby causing weight gain and obesity, genetic predisposition, and enviromental factors. Australian studies have reported the prevalence rates of MetS for people with serious mental illness as ranging between 51% and 68%. The pervasiveness of physical health issues, including weight gain, in mental health consumers has prompted calls for nurse-led health prevention and intervention programs and practices.

Study: The study used a randomised control trial (RCT) to test the effect of a nurse-led intervention on weight gain in people with serious mental illness (SMI) prescribed and taking second generation antipsychotic medication. After ethical approval, 104 participants, recruited to the study from the local area, were consented and randomly allocated to the control or intervention group. The intervention group received a 12 week healthy lifestyle booklet, designed specifically by the researcher. The intervention group also received the healthy lifestyle booklet but also participated in a program of weekly group sessions underpinned by the spirit of motivational interviewing. The weekly sessions consisted of nutrition and exercise education, exercise sessions, support through nurse involvement, and motivational interviewing.

Participants in both the control and intervention group were measured at baseline and at completion of the 12 week program. There were seven outcome measures collected in the study including self reported questionnaires, and body measurements. Body measurements included girth (cm), weight (kg), height (cm), and BMI (kg/m2). Tools administered included the medication compliance questionnaire (MCQ), the Drug Attitude Inventory (DAI-10), the Liverpool University Neuroleptic Side Effect Rating Scale (LUNSERS), and the Medical Outcomes Study Short Form 36 (SF-36v2).

Data analysis: All characteristics were described using percentages for categorical variables. Distribution of numerical variables was assessed for normality and mean and standard deviation was used to describe the characteristic in case of approximate normality. Median and inter-quartile range was used when numerical data was skewed. All characteristics assessed at baseline were compared between intervention and control groups to evaluate the effectiveness of randomisation. Differences in primary outcome measures between baseline and 12 weeks follow-up was compared between intervention and control group using standard bi-variate statistical tests (for example: Chi-square tests, Fisher's exact tests, Chi-square test for trend, and t tests). Statistical analysis was conducted using SPSS version 18.

Results: The results found that the comparison of baseline characteristics for control group (n=50) and intervention group (n=51) demonstrated that the randomisation process was successful. The majority of study participants (n=101) at baseline self reported a weight problem (n=65, 64.4%), while quite a few more reported previously trying to lose weight (n=81, 80.2%), with participants equally attempting exercise (n=22, 21.1%), diet change (n=23, 22.1%) and exercise and diet combined (n=31, 29.8%), in an attempt to lose weight. The data analysis of the outcome measures for the control group (n=50) and intervention group (n=51), although not statistically significant, demonstrated small positive changes in the predicted direction. There was a mean weight change of - 0.74 kg (SD=3.78 kg, p=0.167) at 12 weeks for the intervention group (n=51), while the control group (n=50) had a mean weight change of - 0.17 kg (SD=3.36, p=0.729) at 12 weeks.

Conclusion: The recruitment and data collection component of this study was conducted over an 18 month time period. The results of the study, while not statistically significant, have shown a positive outcome for participants in the intervention group, with weight measurements indicating small losses. The comparison of baseline characteristics for the control group (n=50) and the intervention group (n=51), demonstrated that the randomisation process was successful. The questionnaire results show that participants of this study were mostly compliant with their psychotropic medication (DAI-10), were able to 'tolerate' their antipsychotic medication and any side effects experienced (LUNSERS), and were 'actively participating in their medication intake' (MCQ). The SF-36v2 results show the participants' self reported physical and mental health as within the population norm scores collected in Australia in 2004. Researcher observations found a willingness to be engaged in the program and participant motivation to be involved in healthy lifestyle changes.

Recommendations: A similar study conducted over a longer period of time may find significant results. As this intervention was only conducted over 12 weeks, it is recommended future studies should implement the intervention over a period of 24 weeks or more. As the study was a randomised control trial formally qualitative data was not collected on the experience of weight gain for people with a serious mental illness prescribed and taking second generation antipsychotic medication. Qualitative research could offer deeper insight into the experience of weight gain, while also identifying individual stages of change. Further, research utilising the Transtheoretical model of change (TTM) and the six stage process – pre-contemplation, contemplation, preparation, action, maintenance and termination- to assess the individual would enable the design of a program that was relevant to the change stage for each participant. Supplementary individual support for participants, such as shopping support or cooking classes, could also increase participants' ability to choose healthy lifestyle behaviours.

Item ID: 29821
Item Type: Thesis (PhD)
Keywords: mental illness; metabolic syndrome; antipsychotic medication; nurse-led intervention; healthy lifestyle
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Additional Information:

Appendices A and B (administrative documentation) are not available through this repository.

Publications arising from this thesis are available from the Related URLs field. The publications are:

Chapter 3. Park, Tanya, Usher, Kim, and Foster, Kim (2011) Description of a healthy lifestyle intervention for people with serious mental illness taking second-generation antipsychotics. International Journal of Mental Health Nursing, 20 (6). pp. 428-437.

Date Deposited: 16 Oct 2013 06:04
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1110 Nursing > 111005 Mental Health Nursing @ 100%
SEO Codes: 92 HEALTH > 9202 Health and Support Services > 920209 Mental Health Services @ 100%
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