The hospital's Ethics Committee approved the protocol, which was implemented following a very rigorous routine; the clinicians had the monthly live performance programme in advance, enabling the team to set up the conditions for carrying out the research. After the clinicians performed a clinical assessment of hospitalised patients, the list of nominated patients was sent to us one day before the concert; we randomised the names of the patients, thus ensuring that no bias was introduced when dividing the patients into two groups:

- ❑ group formed by patients who remain in the ward at the time of the live performance; ❑ group formed by patients who remain in the ward at the time of the live performance;
- ❑ group integrated by patients who attended the concert ❑ group integrated by patients who attended the concert
- ❑ music was performed in the public area of the hospital's ground floor, and did not reach ❑ music was performed in the public area of the hospital's ground floor, and did not reach patient's in the second floor ward which looked after patients with HIV;
- ❑ consent of the patient was requested before being included in the study; ❑ consent of the patient was requested before being included in the study;
- ❑ hour before the music started, the clinicians collected a blood sample from each patient ❑ hour before the music started, the clinicians collected a blood sample from each patient in both the control and the study groups;
- ❑ second blood sample was taken within an hour after the concert had ended; ❑ second blood sample was taken within an hour after the concert had ended;
- ❑ two blood samples from each subject were analysed in the hospital's laboratory. ❑ two blood samples from each subject were analysed in the hospital's laboratory.

##### Measurements

- ❑ to establish the number of CD4 and CD8 lymphocyte cells per mm ; ❑ to establish the number of CD4 and CD8 lymphocyte cells per mm ;
- ❑ percentage of each subset in relation to the total number of lymphocytes. ❑ percentage of each subset in relation to the total number of lymphocytes.
- ❑ data was entered into a special database and analysed statistically. Full details of the ❑ data was entered into a special database and analysed statistically. Full details of the statistical tests applied can be found in The Appendix.

##### Results

The results showed that there were no differences in the number of CD4 cells/mm before and 3 after the concert in either of the two groups of patients. Interestingly, however, live performances appear to have an effect on CD8 lymphocytes or killer cells. The number of this type of cell was higher in the blood sample taken after the patient was exposed to music than in the first sample, whereas in the control group the number of CD8 cells in the first and second blood samples remained unchanged. The clinical significance of this finding is difficult to assess for two main reasons: a) although the total number of killer cells had increased in those patients who experienced live music, the percentage of this subset in relation to the total number of white cells did not change, and b) because it is difficult to draw definitive conclusions due to the small number of patients tested. Initially, this study aimed to recruit 30 to 40 patients. The complexity of the clinic, including unforeseen problems with staff resources in taking blood samples, and the nature of the disease

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