Objectives: 1) To ascertain the stability of a diagnosis of compulsive water drinking (CWD) among psychiatric rehabilitation inpatients after a period of four years. 2) To ascertain the discharge status of CWD inpatients in comparison with matched control inpatients after a period of four years.

Method: A follow-up study was performed. Urine specific gravity testing was used to determine CWD status among psychiatric rehabilitation inpatients. Originally, 21 CWD subjects were identified, and 21 age and sex matched control subjects were selected from the non-CWD rehabilitation inpatients. Four years later those CWD and control subjects successfully traced (18 and 15 respectively) were retested for CWD. In addition each subject's living situation (inpatient or community resident) was recorded. Chi-square, Odds Ratio, and Fisher's Exact Test were used as tests of statistical significance.

Results: While the original CWD status was associated with the follow-up CWD status using Chi-square (p < 0.05), there was no statistical association using Odds Ratio (95% CI was 0.95 to 71.6). Half of the 18 original CWD subjects retested negative for CWD. Two of the 15 control subjects retested positive for CWD. Original CWD status was not associated with subsequent living situation, however all seven community dwelling subjects (four original CWD, three original controls) that were successfully traced were negative for CWD.

Conclusions: CWD status may not be as stable as implied in the literature.