The study was an optional part of a prospective, cross-sectional, cohort study aimed to describe ambulatory surgery practice in Finland, carried out between February and April 2007 at 14 day surgery units . Consecutive Finnish or Swedish speaking patients, aged 18 years or older scheduled for day-case inguinal hernia repair (Hernia group), laparoscopic cholecystectomy (LCC group), arthroscopic procedures of the knee (Knee group) or shoulder joints (Shoulder group) were asked to participate. The aim was to recruit 200 patients during the study period, 50 patients from each surgical group. Health-related quality of life was assessed pre- and postoperatively using the validated Finnish version of the RAND-36 questionnaire . There were no changes in standard care during the study period. Ethical Committees of all participating hospitals accepted the approval given by the Ethical Committee of the Hospital District of Northern Savo.
Patients were recruited to the study at least one week before surgery by telephone or at a preoperative visit by anesthesiologists or nurses that were in charge of the study at different units. Patients gave their written consent after receiving oral and written information about the study protocol.
The preoperative questionnaire was returned on the day of the operation. The postoperative questionnaire was given to patients before discharge from the ambulatory surgery units with instructions to be filled-in and returned in a prepaid envelope one week after the end of the sick leave, or a comparable time. Only patients that returned both questionnaires were included in the analyses. Non-responding patients were not contacted.
Patient and procedure characteristics were documented on separate standardized sheets by nurses at the ambulatory surgery units. An extranet database was provided for the study by Intensium Ltd., a Finnish healthcare IT solution and service provider specialized in benchmarking.
The RAND-36 instrument is composed of 8 health dimensions including altogether 36 items. The 10-item dimension of Physical Functioning measures health-related limitations due to physical activities, the 4-item dimension of Role Limitations Due to Physical Health Problems measures the extent to which health interferes with working and other daily activities, the 2-item dimension of Pain measures pain frequency and its interference on health, the 5-item General Health dimension measures health in general, the 5-item dimension of Emotional Well-being measures general mood, depression, anxiety and well-being; the 3-item dimension of Role Limitations Due to Emotional Problems measures the extent to which emotional problems interfere with work and daily activities, the 2-item dimension of Social Functioning measures how health interferes with social activities, and the 4-item Vitality dimension measures how energetic or tired and worn out the patient feels. In addition one item inquires about the individuals` present health state compared to 12 months ago [17, 18]. All items are scored from 0 to 100, with high scores indicating good quality of life and high level of functioning . Of the 36 items, 20 are time-related. In the present study time-related items covered the preceding four weeks preoperatively and one week postoperatively.
The score for each health dimension is the mean value of the item scores included in it. According to general recommendations, mean dimension scores for each patient were calculated only when the minimum number of items required for each specific dimension were answered . Results are expressed as means and standard deviations.
Intergroup comparisons between pre-and postoperative dimension scores were performed using the Wilcoxon test for two related samples. P values less than 0.05 were considered statistically significant. A change of at least six points in mean scale scores was considered clinically important. The estimate for clinically important difference was obtained from the literature [17–19]. According to expert opinion, a change of 6-10% on the breath of a relevant instrument scale, or a difference of 10 in median scores is considered clinically important.