Life-table analysis (time until fall) was performed using the LIFETEST procedure (SAS Institute Inc.; Cary, NC). Subject death and end of follow-up in EMRs were treated as censored events. Comparison of survival curves was accomplished using the log-rank statistic. To generate a user-friendly predictive rule, intervals of 5-year age cutoff values (eg, aged 55, aged 60, aged 65 years) were used for survival comparisons. The MMS is calculated in multiples of 5, hence, all possible score cutoffs were considered in survival comparisons. The 2-sample t test was performed for comparison of mean age and MMS between groups and reported as mean ± SD. A P value < .05 was considered statistically significant. Statistical analysis was performed using SAS Enterprise Guide 5.1.
Results
A search of JCMMVH EMRs yielded 270 patients with a diagnosis of AF discharged from the hospital during 2006. Seventy-seven patients were excluded from analysis for the following reasons: dead at time of discharge, 28; transient (persisting < 24 hours) AF associated with an acute medical illness, 12; referred solely for a procedure, 19; mechanical heart valve, 2; patient declined to take anticoagulation therapy, 2; hemorrhagic stroke, 1; bleeding esophageal varices, 1; lacking MFS documentation, 10; and no postdischarge follow-up documented, 2. All subjects except 1 were male. Both the age and MMS of subjects represented non-normal distributions (Anderson-Darling statistic 1.8, P < .001; and 6.7, P < .005). The median subject age was 74 years; the median MMS was 25.
During the approximately 7-year follow-up period (follow-up range 2-2,545 days), 59 of the 193 subjects (31%) fell. No fall resulted in severe bleeding or death. The mean age of subjects who fell was 73.0 ± 10.3 years compared with 71.6 ± 10.5 years for nonfallers (P = .40). Likewise, the mean MMS for subjects who fell was 34.1 ± 22.3 compared with 30.3 ± 19.9 for nonfallers (P = .24). The mean time until first fall (mean survival) was 725 ± 642 days; whereas the mean length of follow-up for people who did not fall (including those censored due to death) was 1,050 ± 869 days. Subject age and MMS were positively correlated, though weakly (Pearson r = 0.36; Spearman r = 0.37).