Data extraction

As no trials used measures of global change, data were extracted from psychometric tests measuring changes in cognition and behaviour. It was only possible to use one measure of cognition or behaviour from each trial in the meta-analysis, therefore a selection process was necessary to identify the most appropriate scale in trials which used more than one. Cognitive tests were chosen using the following, in decreasing order of importance: i) standardised cognitive tests, ii) orientation tests, iii) short-term memory tests, iv) information tests, v) any test of cognition using some of ii)-iv). Similarly, behavioural tests were selected using i) standardised behavioural tests, ii) tests of activities of daily living (ADL) / adaptive social behaviour. Discussion between the reviewers were used to resolve any queries. Baseline and follow-up data (means and standard deviations) from each scale were required for meta-analysis. In some cases, these were not provided in the papers, and authors were contacted directly.

Each study was critically evaluated by two reviewers, considering various factors which might affect the methodological quality of the study. Quality was assessed according to the four criteria outlined in the Cochrane Collaboration Handbook (Mulrow & Oxman, 1996); selection bias, performance bias, attrition bias and detection bias. Descriptive details were extracted using a standard data extraction form.

2.2.4. Analyses

RevMan 3.0 (Update Software, 1996) was used, which involved meta-analyses (called “metaview”). For the RO review, analyses were adjusted to the random effects model, due to the heterogeneity of trials. Because trials used different tests to measure the same outcomes. Standardized Mean Differences (SMDs) were used. These were calculated by dividing the difference between the treatment and control means by the pooled standard deviation within each study, thus enabling them to be compared to the other trials in a standardized way. For the RT review, because only one trial was entered, the Weighted Mean Difference (WMD) was used. This calculated the difference between the treatment and control means, divided by the standard deviation. Further, the fixed effects model was used as the single trial implied no issues of heterogeneity.

2.3.

RO review

2.3.1. Selection of trials

From the information in the title and abstract, 43 publications were identified as possibly relevant following the literature search. A reviewer and co-reviewer independently assessed eligibility. 22 publications were immediately excluded: 4 were not trials, 5 examined non­ dementia populations, 4 were case studies, 2 were observational studies and 7 were uncontrolled. The remaining 21 trials were all controlled, but of these 6 were clearly not randomized (subjects were "selected" or "chosen") and 2 looked at 24-hour RO only. 6 trials had no mention of randomisation, and authors were contacted and asked directly. One author responded with details of randomisation (Ferrario et al, 1991). The 7 remaining controlled

trials all included the term(s) "randomized" or "randomly assigned". It was decided that this was acceptable for inclusion into the review. Therefore, 8 RCTs were included.

2.3.2. Quality of included studies

A number of biases affected all the included trials. Details of selection bias (bias due to group allocation, ie. no randomisation or poor randomisation concealment), attrition bias

(bias due to dropouts) and detection bias (bias due to assessors’ awareness of group allocation) are summarized in table 2. Attrition bias was generally as expected in dementia populations, although over a third dropped out in the study of Wallis et al (1983). For this to be investigated effectively, an ‘intention to treat analysis’ (see 6.5.1.) would have been required, although none of the trials included such analyses. In half of the trials, assessments were made either by people familiar with group membership, or no details were given; hence introducing detection bias.

Performance bias, which refers to bias created by people’s expectations of treatment, was difficult to evaluate. With psychological interventions, unlike pharmacological treatments, it is impossible to blind patients and staff totally to treatment. Patients may be aware that they are being treated preferentially, and staff involved may have different expectations of treatment groups. Both these factors could affect patients’ performance. Additionally, independent assessors may be given clues about group assignment from patients during the assessments. The extent of patients’ awareness of treatment depends greatly on how much information is given to them, and their level of comprehension.

There could also have been contamination (elements of one treatment leaking into another) when groups were not held in a separate room, or when staff accidentally brought ideas from one group to another. The latter effect would be reduced with clear therapeutic protocols, the existence of which was not mentioned in any of the studies; although in a personal correspondence. Woods (1998) reported that one was used. Most authors said that the RO groups were held in separate areas, reducing the chance of contamination (Baines et al, 1987; Ferrario et al, 1991; Hanley et al, 1981; Wallis et al, 1983; and Woods, 1979). It is unclear as to where groups were held in the other studies.

2.3.3. Meta-analysis

Of the 8 studies, only 6 could be entered into Metaview. The others (Baldelli et al, 1993; and Hanley et al, 1981) did not include the statistics needed for the analysis, and authors were contacted with no response. These 6 RCTs yielded a total of 125 subjects (67 treatment subjects, 58 controls). Results for cognition were significant in favour of treatment (see Figure 2). The SMD was -0.59, with a 95% Confidence Interval (Cl) of [-0.95, -0.22]. A Cochrane statistical advisor stated that comparing the SMD with a normal distribution indicated that the average score for participants in the treatment group was better than 72% of the control participants’ scores. The results were highly influenced by the largest study (Breuil et al, 1994), in which results significantly favoured treatment (SMD= -0.71, 95% Cl [-1.26, -0.17]). Although the remaining trials did not individually reach significance, trends were positive and the combined cognitive result significantly favoured RO. All trials contained cognitive measures, with a total of 125 participants.

Only 3 trials used a measure of behaviour. The combined result was again significant in favour of treatment (see Figure 3). The SMD was -0.64, 95% Cl [-1.20, -0.08], with a total of 57 participants entered into the analysis (33 experimental, 24 control). Comparing the SMD with a normal distribution indicated that the average score for participants in the treatment groups were better than 74% of the control participants’ scores. Trials did not individually reach significance, but the trend favoured RO.

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