Co-morbidity As a Predictor of Outcome in Patients with Idiopathic Normal-pressure Hydrocephalus

Introduction: A critical question in the diagnosis and treatment of idiopathic normal-pressure hydrocephalus (iNPH) is which preoperative factors can most reliably predict outcomes following shunt insertion. The number and type of co-morbidities are increasingly being viewed as important predictive indicators.

Materials And Methods: Between 1997 and 2005, 100 patients were implanted with a gravitational ventriculo-peritoneal shunt as a treatment for iNPH. All coincident disease processes were recorded. Eighty-two of these patients underwent follow-up of 2 years post-operation. The results of this prospective follow-up examination (Kiefer Score, NPH Recovery Rate) were compared with the preoperative Co-morbidity Index (CMI).

Results: Of the patients with a CMI score of 0-1 (n = 18), 67% experienced an excellent outcome, 28% a good outcome, and 5% and 0% fair and poor outcomes, respectively. A CMI score of 2-3 was associated with markedly poorer outcomes (n = 33); 42% excellent, 30% good, 18% fair and 10% poor. A score of 4-5 was related to 14% excellent, 27% good, 23% fair and 36% poor outcomes (n = 22). Remarkably, a few patients scoring between 6 and 8 on the CMI scale experienced a favorable outcome. The outcomes for this latter group were 0% excellent, 10% good, 45% fair and 45% poor (n = 9).

Conclusion: Co-morbidity is a statistically significant predictor of the quality of clinical outcome for patients with iNPH undergoing shunt therapy.