Predicting shunt failure on the basis of clinical symptoms and signs in children

Object. In evaluating pediatric patients for shunt malfunction, predictive values for symptoms and signs are important in deciding which patients shou ld undergo an imaging study, whereas determining clinical findings that cor relate with a low probability of shunt failure could simplify management. Methods. Data obtained during the recently completed Pediatric Shunt Design Trial (PSDT) were analyzed. Predictive values were calculated for symptoms and signs of shunt failure. To refine predictive capability, a shunt score based on a cluster of signs and symptoms was derived and validated using m ultivariate methods. Four hundred thirty-one patient encounters after recent shunt insertions we re analyzed. For encounters that took place within 5 months after shunt ins ertion (early encounters), predictive values for symptoms and signs include d the following: nausea and vomiting (positive predictive value [PPV] 79%, likelihood ratio [LR] 10.4), irritability (PPV 78%, LR 9.8), decreased leve l of consciousness (LOC) (PPV 100%), erythema (PPV 100%), and bulging fonta nelle (PPV 92%, LR 33.1). Between 9 months and 2 years after shunt insertio n (late encounters), only loss of developmental milestones (PPV 83%, LR 36. 7) and decreased LOC (PPV 100%) were strongly associated with shunt failure . However, the absence of a symptom or sign still left a 15 to 29% (early e ncounter group) or 9 to 13% (late encounter group) chance of shunt failure. Using the shunt score developed for early encounters, which sums from 1 to 3 points according to the specific symptoms or signs present, patients wit h scores of 0, 1, 2, and 3 or greater had shunt failure rates of 4%, 50%, 7 5%, and 100%, respectively. Using the shunt score derived from late encount ers, patients with scores of 0, 1, and 2 or greater had shunt failure rates of 8%, 38%, and 100%, respectively. Conclusions. In children, certain symptoms and signs that occur during the first several months following shunt insertion are strongly associated with shunt failure; however, the individual absence of these symptoms and signs offers the clinician only a limited ability to rule out a shunt malfunctio n. Combining them in a weighted scoring system improves the ability to pred ict shunt failure based on clinical findings.