Increased fall risk in patients with neovascular age‐related macular degeneration: a three‐year follow‐up study

Previous studies showed that neovascular age-related macular degeneration (AMD) is the leading cause of severe visual impairment and is associated with injurious falls, postural instability and reduced gait speed (Wood et al., 2009; Rovner et al., 2011; Cruess et al., 2007). However, only a limited number of studies have explored the relationship between neovascular AMD and falls (Wood et al., 2011; Cruess et al., 2007; Szabo et al., 2010). Therefore, using a population-based dataset (Longitudinal Health Insurance Database 2005) from Taiwan, we conducted this study to examine the relationship between neovascular AMD and the risk of subsequently falling during a 3-year follow-up period. This retrospective cohort study consisted of a study group and a comparison group. For the study group, we selected 1717 patients aged ≥40 years and who had received a first-time diagnosis of neovascular AMD (International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes 362.42, 362.43, 362.52 or 362.53) between 1 January 2002 and 31 December 2010. We defined the date of receiving their first diagnosis of neovascular AMD as the index date. We also selected 8585 comparison patients (five for every patient with neovascular AMD) matched in terms of gender, age group and the year of the index data. We assured that all selected comparison patients did not have a history of AMD. We assigned the first use of ambulatory care in the index year as the index date for the comparison group. As a result, 10,302 study patients, including 1717 study patients and 8585 comparison patients, were enrolled in this study. We individually followed each patient for a 3-year period starting from their index date to identify those patients who subsequently received a diagnosis of a fall (ICD-9-CM External Cause of Injury Codes E880~E888). We found that the incidence rate of falls was 2.85 (95% CI: 2.27~3.52) per 1000 person-years among all sampled patients. Specifically, the incidence rates of falls per 1000 person-years were 4.75 (95% CI: 3.01~7.13) and 2.47 (95% CI: 1.81~3.18), respectively, for patients with and those without neovascular AMD (Table 1). The log-rank test showed that there was a statistically significant difference in the 3-year fall-free accumulated survival rates between the two groups (p =0.009). Results of the stratified Cox proportional analysis revealed that compared to patients without neovascular AMD, the hazard ratio (HR) of falls during the 3-year follow-up period was 1.66 (95% CI: 1.01~2.74) for patients with neovascular AMD than comparison patients after censoring those who died during the follow-up period and adjusting for patients’ monthly income, geographical location, urbanization level, hypertension, diabetes, hyperlipidaemia, stroke and mental illness. To the best of our knowledge, this is the first population-based study to evaluate the relationship between neovascular AMD and the subsequent risk of a fall during a 3-year follow-up period in an Asian country. We found that the adjusted HZ for a fall during the 3-year follow-up period for subjects with neovascular AMD was 1.66 compared to those without neovascular AMD. The specific mechanisms which underlie this relationship between neovascular AMD and falls are still unclear. Poor visual acuity and contrast sensitivity, low visual reaction times and balance problems have been hypothesized mechanisms linking neovascular AMD and falls (1996; Ivers et al., 1998; Szabo et al., 2010; Wood et al., 2011). Further studies are needed to confirm our findings and explore the underlying mechanisms. In summary, this study revealed the relationship between neovascular AMD and the subsequent risk of a fall. We suggest that clinicians consider alerting their patients with neovascular AMD to the potential risks of a fall.