Thirteen trials with 10,057 participants (range 146 to 3,382) were included. Follow-up times ranged from three to 96 months; only three trials had follow-up that exceeded 12 months. Trial quality varied. Most trials were considered to be of moderate quality (three to five domains at low risk of bias). The main potential sources of bias were lack of blinding of participants and incomplete outcome data.
For the three studies that reported reduction in Framingham 10-year risk score there was no evidence that telehealth interventions reduced cardiovascular risk (SMD -0.35, 95% CI -1.97 to 1.27; Ι²=82%). Eight trials reported systolic blood pressure lowering, with no statistically significant evidence of a benefit of telehealth (SMD -1.22 mmHg, 95% CI -2.80 to 0.35; Ι²=61%).
Six studies reported total cholesterol reduction with no statistically significant benefit of telehealth (SMD -0.07 mmol/L, 95% CI -0.19 to 0.06; Ι²=45%). Four trials reported high-density lipoprotein (HDL) cholesterol reduction, again with no evidence of a benefit of telehealth (SMD -0.01 mmol/L, 95% CI -0.03 to 0.02; Ι²=49%). Four trials reported reduction in smoking, with no evidence of a benefit of telehealth (OR 1.09, 95% CI 0.82 to 1.44; Ι²=0).
Meta-analyses for other outcomes were not performed because of a lack of suitable data. Some results from specific trials were presented.