[Applying the hierarchical linear model in longitudinal studies: an example of symptom distress in women who had undergone a hysterectomy].

The purpose of this study was to introduce the Hierarchical Linear Model (HLM) and apply it to the topic of symptom distress in women who had undergone a hysterectomy. HLM was developed to analyze multilevel data and included a longitudinal study, which focused in particular on unbalanced design. A quasi-experimental design was conducted. Data on symptom distress in women who had undergone a hysterectomy (experimental group) and those who had not (control group) were collected over a six-week period and analyzed using HLM. Findings indicated that the experimental group had a quadratic trajectory in physical distress changes and a negative linear trend in psychological distress, both of which differed significantly from the control group. Additionally, physical and psychological distress influenced one another in three measurement variables, and physical distress in the experimental group actually improved over the six week period. Using HLM was able to estimate the different trajectories for each subject in the experimental group. This study shows that HLM can be applied effectively in longitudinal studies.