Seven trials were included in the review (524 patients, range 10 to 279): six trials in dialysis patients and one trial in non-dialysis patients. Five trials scored 3, one trial scored 2 and one trial scored 1 on the Jadad scale. All trials were randomised. Most trials had adequate randomisation methods and reporting of withdrawals and drop-outs. None of the trials met the criteria for blinding. One trial had adequate allocation concealment. Follow-up ranged from four weeks to 12 months.
Phosphorus levels: Compared with control, education/counselling was associated with a statistically significantly greater reduction in end-study phosphorus levels (mean difference -0.72, 95% CI- 1.11 to -0.33; seven RCTs, Ι²=40%).
Subgroup analysis indicated that results were still statistically significant with dialysis patients (mean difference -0.75, 95% CI- 1.23 to -0.28; six RCTs, Ι²=49%) but not with non-dialysis patients (one RCT).
Sensitivity analysis indicated that trials with a follow-up of more than four months had a greater decrease in phosphorus levels (mean difference -1.07, 95% CI- 1.49 to -0.64; four RCTs, Ι²=0%). Trials with a follow-up of less than four months showed a reduction in phosphorus levels that was not statistically significant (three RCTs).
Calcium-phosphate product levels: Compared with control, education/counselling was associated with a statistically significantly greater reduction in calcium-phosphate product levels (mean difference -5.23, 95% CI -9.48 to -0.98; five RCTs, Ι²=48%).
Subgroup analysis indicated that results were statistically significant with dialysis patients (mean difference -5.75, 95% CI -11.08 to -0.42; four RCTs, Ι²=58%) but not with non-dialysis patients (one RCT).
Sensitivity analysis that excluded one trial to reduce heterogeneity found that the results were not significant (overall and by subgroup).