Postural Sway and Falls in Parkinson’s Disease: A Regression Approach Maarit Matinolli, MD, 1 * Juha T. Korpelainen, MD, PhD, 1 Raija Korpelainen, PhD, 1,2,3 Kyo ¨sti A. Sotaniemi, MD, PhD, 1 Minna Virranniemi, MD, 1 and Vilho V. Myllyla ¨, MD, PhD 1 1 Department of Neurology, University of Oulu, Oulu, Finland 2 Department of Sports Medicine, Deaconess Institute of Oulu, Oulu, Finland 3 Department of Public Health and General Practice, University of Oulu, Oulu, Finland Abstract: A population-based study was designed to evaluate the clinical associates of postural sway and to identify the risk factors for falls in Parkinson’s disease (PD). From a total population of 205,000 inhabitants, 215 PD patients were iden- tified of which 120 home-dwelling cases were finally included in the study. Medical data were collected and patients were clinically examined and tested for static balance using an inclinometric device. Recent falls occurred in 40 (33%) of the subjects and 27 (23%) subjects were recurrent fallers. The fallers had a significantly larger sway area (P = 0.021) and a larger maximum deflection in anterior–posterior (P = 0.016) and lateral directions (P = 0.006) than the nonfallers. A sig- nificant correlation was found between the sway measures and the UPDRS total score, motor subcore and UPDRS “bradyki- nesia” item. A higher UPDRS total score (OR: 1.04, 95% CI: 1.01–1.07) and an increased sway area (OR: 1.25, 95% CI: 1.02–1.54) were independent risk factors for recent falling in PD. In addition, the duration and severity of PD, antiparkinso- nian medication, recent falling and the use of a walking aid were associated with increased sway measures. The results can be used to identify PD patients who are at a risk of falling. Both antiparkinsonian medication and nonmedical treatment should be optimized to reduce falls in PD. © 2007 Movement Disorder Society Key words: Parkinson’s disease; postural sway; balance impairment; falls. Parkinson’s disease (PD) is a common neurodegenera- tive disease in the elderly population. Balance impair- ment is one of the cardinal symptoms of PD, placing patients at an increased risk of falling. 1 Falls often lead to injuries, fractures, increased dependency, and fear of falling, and thereby to a decreased quality of life. 2–6 Several components of postural control, including the latencies and amplitudes of postural response, visual, proprioceptive, and vestibular control of postural re- sponses, biomechanical properties of muscles and joints, and dynamic control, may be affected in PD patients. 7 Impairment of postural reflexes reduces the limits of stability and is associated with difficulty in executing and timing responses to external challenges and unexpected perturbations. 8 Measurement of postural sway can be used to quantify postural balance impairment. Postural sway, especially in lateral directions, appears to be sig- nificantly greater in PD patients than in healthy controls, and to correlate with the duration and severity of the disease. 9 Several previous reports also state that body sway is an important risk factor for falling. 10 –14 The pathophysiological background of balance disturbance in PD remains unknown, but it may be partly nondopam- inergic in origin. 15 In retrospective studies 38 to 64% of PD patients have reported falls. 8,16,17 However, recent prospective studies suggest that even a higher proportion (51– 68%) of PD patients experience falls. 5,6,18 Previous falls, fear of falling, dementia, disease duration, and loss of arm swing have been identified as independent risk factors for falls in PD. 5,6 Using a regression approach the present study aimed to identify the clinical determinants of increased postural sway and falling in PD. *Correspondence to: Maarit Matinolli, Department of Neurology, University of Oulu PO Box 5000, 90014 University of Oulu, Finland E-mail: hmkemppa@mail.student.oulu.fi Received 15 January 2007; Revised 21 May 2007; Accepted 22 May 2007 Published online 27 June 2007 in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/mds.21633 Movement Disorders Vol. 22, No. 13, 2007, pp. 1927–1935 © 2007 Movement Disorder Society 1927