Table 1

Characteristics of study cohort during study period*

Total number of enrollees6,185 (100.0)
Enrollees who used shared medical record1,990 (32.2)
Age at baseline [mean years ± SD (range)]75.2 ± 6.73 (65–101)
    65–691,539 (24.9)
    70–741,550 (25.1)
    ≥753,096 (50.1)
Female3,150 (50.9)
Low neighborhood SES status1,500 (26.8)
>30 min driving time from clinic400 (7.2)
Morbidity category at baseline§
    Low or very low236 (3.8)
    Moderate2,676 (43.3)
    High1,764 (28.5)
    Very high1,509 (24.4)
PCP's percent of encounters via secure messaging [mean ± SD (range)]18.5 ± 8.1 (1.3–49.5)
Insulin use at baseline1,792 (29.0)
Change during study period
    From “moderate or lower” to “high” or “very high” morbidity2,402 (38.8)
    To new PCP with 10% higher level use of secure messaging815 (13.2)
    From oral or diet therapy to insulin1,143 (18.5)
Died during study period1,621 (26.2)
  • Data are n (%) unless otherwise stated.

  • *Study period was defined as introduction of SMR (1 August 2003) to end of available data (31 December 2007); values calculated as of beginning of study period unless otherwise noted.

  • †Calculated using 2000 U.S. Census data and address from January 2005; number missing 582 (9.4%).

  • ‡Based on distance between residence and primary clinic >27 linear kilometers as of January 2005; number missing 592 (9.6%).

  • §Based on Johns Hopkins Associated Clinical Groups Resource Utilization Bands.

  • ¶Defined as number of secure messaging threads by PCP divided by PCP's total outpatient encounters plus secure messaging threads, averaged over study period; number missing 86 (1.4%). All other measures missing <1%.