Parents of children with periodic limb movement disorder versus sleep-disordered breathing report greater daytime mood and behavior difficulties in their child: the importance of using ICSD-2nd Edition criteria to define a PLMD study group.

Data from 249 children referred to a pediatric sleep clinic were analyzed. The first question of interest examined whether an International Classification of Sleep Disorders-Second Edition (ICSD-2)-based diagnosis of periodic limb movement disorder (PLMD) or sleep-disordered breathing (SDB) would more strongly associate with parental perceptions of daytime attention and behavior problems in their child. The second question was whether the outcome would differ based on PLMD diagnostic criteria-that is, previously used criteria to define PLMD (Periodic Limb Movement Index [PLMI] < 5 per hour vs. PLMI >or= 5 per hour only) versus the ICSD-2 criteria. Parents of children with ICSD-2-defined PLMD perceived more problems with daytime behavior and attention, more symptoms of internalizing and externalizing, longer sleep latency, and more difficulty falling back to sleep than did parents of children with SDB. Most effects were lost when groups were defined by PLMI alone. The PLMI had acceptable sensitivity but low specificity in diagnosing PLMD.