Small group dynamics and survival on chronic hemodialysis.

Two groups of patients undergoing hemodialysis for chronic renal failure were prospectively studied for twenty-four months. Group A patients (n=12) were dialyzed on Mondays and Thursdays; Group B patients (n=9) on Tuesdays and Fridays. Although patients were supposedly assigned to dialysis groups on a random basis, over a twenty-four month period Group A had significantly more deaths (7 patients) than did Group B (none). This phenomenon is interpreted in the framework of an ongoing intergroup interaction among patients and between patients and staff, as conceptualized in the Tavistock Model propounded by Bion. It is hypothesized that in the dialysis unit, unconscious splitting by the staff led to a bias in patient-group assignment, such that those patients with more severe personality disruption, and "bad" in that sense, were assigned to Group A. Since patients in Groups A and B did not differ significantly in biological or demographic parameters at time of entry into the study, it is suggested that the increasing density of psychopathology in Group A was related to poorer care, more physical morbidity and a decreasing survival rate. Although no intermediary psychobiological mechanisms were defined, these findings suggest a significant interaction between the social, psychological and biological factors determining survival on chronic renal hemodialysis, beginning with the treatment decision and continuing throughout the course of treatment. These phenomena should be studied further and may have important implications for planning patient care and patient-staff interactions.