Ten studies with a total of 1,117 participants were included in the review.
Overall, five studies were positive and five were negative.
Eight studies (three rated 'good', four rated 'fair' and one unrated) provided data on the relationship between intensity of treatment and outcome. Four studies had positive outcomes and four negative outcomes. Compared with the negative studies, significantly more hours of therapy per week and significantly more total therapy hours in a significantly shorter period of time were provided in the positive studies. No significant differences in FCP scores were noted between the negative and the positive trials, so no further analysis was made using this measure. Analysis using the PICA and Token Test outcome measures revealed that the total length of therapy was significantly inversely correlated with the mean change in PICA scores (correlation, r=0.948, P=0.0001, n=9). There was a trend towards the same correlation for the Token Test, but this did not achieve statistical significance. The hours of therapy provided in a week was significantly correlated to greater improvement on the PICA test (r=0.957, P=0.001, n=9) and on the Token Test (r=0.811, P=0.027, n=7). The total hours of therapy received were significantly correlated with mean change in PICA (r=0.958, P=0.0001, n=9) and Token Test (r=0.963, P=0.0001, n=7) scores.