Included studies differed widely according to interventions provided,
measures of diet adherence, dietary advice, nature of the
chronic diseases and duration of interventions and follow-up.
Therefore, data were not pooled statistically. Instead, we present a
qualitative analysis described in a narrative table using vote counting
for each category of interventions (see Additional tables). We
also created forest plots for outcomes from studies comparing a
single or multiple intervention group with a control/usual care
group (see Figure 3; Figure 4; Figure 5). Among the 32 studies
that measured diet adherence outcomes between an intervention
group and a control/usual care group, 32 out of 123 diet adherence
outcomes favoured the intervention group, 4 favoured the
control group whereas 62 had no significant difference between
groups. This result was impossible to assess for 25 diet adherence
outcomes as data and/or statistical analyses needed for comparison
between groups were not provided (Additional tables).