This meta-analysis comprised 19 research articles [15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33]. Of these, eight studies [16,17,18, 21, 24, 29, 32, 33] provided data for two or more guidelines within the same article resulting in 31 datasets for the meta-analysis. Figure 1 illustrates the methodology used to select the studies, while Table 1 provides a summary of the principal characteristics of the included studies.

Fig. 1

Study selection using PRISMA technique

Table 1 Basic characteristics of study population

Patients with IDH exhibited a wide range of cardiovascular outcomes. These included an increased risk of cardiovascular diseases such as myocardial infarction, cerebral infarction, and cerebral hemorrhage. Additionally, there was a heightened risk of cardiovascular disease mortality, coronary heart disease (CHD) and CHD mortality, stroke and its subtypes (hemorrhagic and ischemic), and all-cause mortality. Of these investigations, 17 studies adopted a prospective cohort design [15,16,17,18,19,20,21,22,23,24,25,26,27, 29,30,31, 33], while 2 were cross-sectional analyses [28, 32]. The included studies enrolled between 173 and 2,969,679 participants. Among these studies, the JNC7 guideline [15, 16, 19,20,21,22,23,24,25,26,27,28,29,30,31,32] was the most frequently utilized for diagnosing IDH, followed by ACC/AHA [17, 18, 24, 32, 33] and NICE/ESC [17, 18, 33] guidelines (Figs. 2, 3, 4).

Fig. 2

Random effects forest plot for IDH and risk of CVD among studies using JNC7 guidelines

Fig. 3

Random effects forest plot for IDH and risk of CVD among studies using NICE guidelines

Fig. 4

Random effects forest plot for IDH and risk of CVD among studies using ACC guidelines

The total number of patients diagnosed with IDH using the JNC7, ACC/AHA, and NICE/ESC guidelines were 3,646,490, 255,640, and 248,233, respectively. Cohort studies comprised 4,022,262 enrolled patients, whereas 128,101 participants were included in cross-sectional studies.

Quality of studies and publication bias

All included studies demonstrated high methodological rigor, with quality scores ranging from 7 to 9 (see supplementary material). To assess potential publication bias in the pooled estimates, we first examined funnel plot asymmetry, visually represented in the supplementary material. Significant publication bias was detected in the pooled HRs for CVD mortality in studies following the ACC/AHA guidelines and for all-cause mortality in studies adhering to the JNC7 guidelines.

We further evaluated publication bias using Egger’s test, with detailed results presented in Table 2. Interestingly, no publication bias was found in the pooled HRs for CVD risk, CHD risk and mortality, or stroke risk in IDH patients, regardless of the guidelines followed. Subgroup analyses also did not reveal any notable publication bias, except for CVD mortality in women and the risk of CVD and all-cause mortality in cohort studies.

Table 2 Publication bias assessment using funnel plot and Egger’s test

To address the identified publication bias, we performed a trim-fill analysis, and the adjusted HRs for each relevant analysis are provided accordingly.

Analysis of individual results

In the 19 studies included, IDH ascertainment was done utilizing varying guidelines. Therefore, we performed a meta-analysis exclusively on those studies that adhered to uniform guidelines.

Risk of cardiovascular disease in patients with IDH

Despite an elevated risk of cardiovascular disease (CVD) in patients with isolated diastolic hypertension (IDH), the diagnostic guidelines influenced this observation. Seven studies [19, 20, 22,23,24, 27, 32] adhering to JNC7 guidelines indicated a 45% increased risk of CVD (pooled HR = 1.45, 95% CI 1.17, 1.74, I2 = 94.270%). Similarly, three studies [17, 18, 33] following NICE/ESC guidelines demonstrated a 33% increased risk (pooled HR = 1.33, 95% CI 0.89, 1.77, I2 = 85.358%), comparable to the JNC7 findings. To a lesser extent, analyses of five studies [17, 18, 24, 32, 33] adhering to ACC/AHA guidelines showed a 16% increased risk (pooled HR = 1.16, 95% CI 1.06, 1.25, I2 = 40.272%).

Cardiovascular mortality in patients with IDH

A pooled analysis of 11 studies [15, 16, 21, 23,24,25, 27,28,29, 31, 32] utilizing JNC7 diagnostic guidelines revealed that patients with isolated diastolic hypertension (IDH) had a higher risk of cardiovascular disease (CVD) mortality (pooled HR = 1.54, 95% CI 1.23, 1.84, I2 = 82.645%) compared to three studies [17, 24, 32] adhering to ACC/AHA guidelines (pooled HR = 1.10, 95% CI 0.95, 1.25, I2 = 38.606%). To address the observed publication bias in studies using ACC/AHA guidelines, subsequent trim-fill analysis yielded a pooled HR of 1.01 (95% CI 0.85, 1.17).

All-cause mortality

An extensive examination of five studies [21,