Erythrocyte Distribution Width and Central Corneal Thickness in Patients with Obstructive Sleep Apnea Syndrome

Association between Red Blood Cell Distribution Width and Obstructive Sleep Apnea Syndrome: A Systematic Review and Meta-Analysis

“…The forest plot for RDW values in OSAS and non-OSAS subjects is described in Figure 2. Three studies [46,58,60] reported lower RDW values in OSAS subjects than non-OSAS controls (mean difference range, −0.10 to −0.60), with one reporting a statistically significant difference [60], whereas no between-group difference was reported in another study [57]. In the remaining 16 studies [14,44,45,47-50,52-56,58,61,62], OSAS patients had higher RDW values than non-OSAS subjects (mean difference range, 0.05 to 3.99), with a significant difference in eight [45,47,48,[51][52][53]61].…”

“…Of these, 48 were removed because they did not report the studied endpoint (n = 30), did not include the control group (n = 9), investigated pediatric cohorts (n = 4) or different patient groups (n = 2), or were not written in English (n = 3), leaving 17 articles. Since three additional records were identified from Google Scholar and reference lists, a total of 20 manuscripts [14,[44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] were included in the final analysis (Figure 1). The included studies were published between 2012 [44] and 2022 [60][61][62].…”

“…Since three additional records were identified from Google Scholar and reference lists, a total of 20 manuscripts [14,[44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] were included in the final analysis (Figure 1). The included studies were published between 2012 [44] and 2022 [60][61][62]. The majority were conducted in Turkey (n = 15) [14,[44][45][46][47][48]52,54,55,57,58,60,62], whereas the remaining (n = 5) were conducted in Spain [49], Egypt [50], Pakistan [53], China [56], and Romania [61].…”

“…The included studies were published between 2012 [44] and 2022 [60][61][62]. The majority were conducted in Turkey (n = 15) [14,[44][45][46][47][48]52,54,55,57,58,60,62], whereas the remaining (n = 5) were conducted in Spain [49], Egypt [50], Pakistan [53], China [56], and Romania [61]. Eight studies were retrospective [48,51,52,54,[56][57][58]62] (Table 1).…”

“…A second sub-group analysis based on study design revealed no significant differences (p = 0.53) in RDW values between prospective (SMD = 0.39; 95% CI 0.13 to 0.65, p = 0.002; I 2 = 76.1%, p < 0.001) and retrospective studies (SMD = 0.24; 95% CI −0.6 to 0.55, p = 0.12; I 2 = 93.8%, p < 0.001) (Figure 5), even though the effect size in retrospective studies was not statistically significant. Finally, 13 studies [14,44,45,48,51,52,54,[56][57][58][60][61][62] also reported RDW values based on disease severity. RDW values in OSAS subjects were significantly higher in comparison to non-OSAS controls, in a progressive manner, from mild (SMD = 0.18; 95% CI 0.05 to 0.314, p = 0.006; I 2 = 45.5%, p = 0.037, Figure 6A) to moderate (SMD = 0.39; 95% CI 0.10 to 0.67, p = 0.009; I 2 = 89.1%, p < 0.001, Figure 6B) and to severe disease (SMD = 0.56; 95% CI 0.30 to 0.81, p < 0.001; I 2 = 88.4%, p < 0.001, Figure 6C).…”