Objectives: To review systematically studies of late-onset polio sequelae on the course of functional status and muscle strength over time and to identify prognostic factors of change.
Data sources: We conducted a computerized literature search up to July 2004 in MEDLINE, EMBASE, CINAHL, Web of Science, PsychInfo, and the Cochrane controlled trial register using the key words: postpolio, postpoliomyelitis, postpoliomyelitis syndrome, post poliomyelitis muscular atrophy, and poliomyelitis.
Study selection: Reports were selected by 1 reviewer if the study involved subjects with a history of poliomyelitis, the outcome measures described functional status or muscle strength, and follow-up was for at least 6 months.
Data extraction: Studies were summarized with regard to population, design, sample size, outcome measures, results, and methodologic scores. Overlap in populations between studies was checked.
Data synthesis: Of 71 potentially relevant studies, 19 were included (2 on functional status, 15 on muscle strength, 2 on both muscle strength and functional status). Two studies on the course of functional status had sufficient quality and reported inconsistent results. Four studies on the course of muscle strength had sufficient quality. Two studies reported a decline in strength and 2 reported no change. Decline in strength was only reported in studies with a follow-up period longer than 2 years. One study reported extent of paresis as a prognostic factor for change in perceived physical mobility.
Conclusions: Conclusions cannot be drawn from the literature with regard to the functional course or prognostic factors in late-onset polio sequelae. The rate of decline in muscle strength is slow, and prognostic factors have not yet been identified. Long-term follow-up studies with unselected study populations and age-matched controls are needed, with specific focus on prognostic factors.