[Metric characteristics of the Professional Quality of Life Questionnaire [QPL-35] in primary care professionals]

To assess the internal consistency, discriminative capacity and factorial composition of the Professional Quality of Life Questionnaire (QPL-35) in a population of primary care professionals.We performed a cross-sectional analytical study in a primary care area in Madrid from 2001 to 2003. Random sampling of 450 healthcare professionals was performed on 2 occasions. The sample was stratified into 3 groups: group I (clinicians, pharmacologists, psychologists), group II (nurses, midwives, physiotherapists, social workers) and group III (administrative staff, porters, auxiliary nurses). The self-administered questionnaire QPL-35 was sent in January 2001 and January 2003 and on each occasion the questionnaire was sent again 1 month later. The percentages of total responses and responses per item were studied. We also studied the distribution of each answer by examining the floor effect and ceiling effect, as well as the factorial composition based on a previous validation study.Five hundred sixty-three questionnaires (62.6%) were returned. All the questions had a response rate of more than 96%. At least one unanswered question was found in 22.0% of the questionnaires, and at least 2 were unanswered in 7.1%. The distribution of the answers did not fit normal distribution in any of the cases. The floor effect was present in questions related to management support and the ceiling effect was found in those related to motivation. The factorial analysis found 3 factors that explained 39.6% of the variance in the total number of questions. These factors were very similar to those of the previous validation study: management support, perception of workload and intrinsic motivation explained 17.0%, 13.2% and 9.4% of the variance, respectively. Internal consistency was high for each factor (Cronbach's alpha0.7) and for the total score (Cronbach's alpha = 0.81).The metric properties of the QPL-35 are maintained in different environments. This questionnaire can be recommended as a tool to measure and compare quality of professional life in primary care.