We identified 2381 articles from our systematic search for related literature. After removing duplicates, 986 articles were screened based on title and abstract. Finally, 30 articles were assessed for eligibility. Some related articles were available with two different versions [29-32]. We excluded the version containing the less comprehensive data [29, 32].. Some studies were also excluded because of the study methodology, for example because of assessing the effect of Quran recitation only after surgery [34], or the intervention was a combined model and it was not possible to separate the data for Quran recitation for example Quran recitation with aromatherapy [35] or Quran recitation with its translation [33]. Reasons for exclusion of the other studies from the review were: implementation of different assessment tools, different outcome measures, different publication types and not studying elective surgeries. After reviewing the full text of eligible studies, twelve RCTs were critically appraised. Finally, a total of twelve studies were included in the qualitative synthesis and nine studies were included for the quantitative synthesis [30, 31, 36-42]. The flow diagram of the study is shown in the Figure 1.
The range of patient ages was 25 to 63 years old. All studies investigated the effect of Quran recitation on the reduction of anxiety in the elective surgeries. In eight studies (66.7%), the experimental group received only Quran recitation, whereas in three studies (25%), there were two experimental groups receiving Quran and music [30, 38, 41] and one study receiving Quran recitation and its translation [31]. All the studies were conducted in Iran, as all studies from other Arabic-speaking countries were eliminated in the study selection process as none of them studied elective surgeries. The characteristics of the sample and the level of anxiety before and after intervention are shown in Table 2.
Table 2. State anxiety of included Studies
Quality of studies
Two authors (FSG & MG) independently appraised the quality of studies. The quality of the majority of studies (83.3%) was moderate to high, with less than 17% of studies having low quality (Table 3). Allocation blinding was unclear in most studies (75%). Blinding of participants was not possible due to the nature of study, as participants were aware of the intervention at the time, but in some studies, the researchers wore headphone when assessing patients in the intervention and control groups during the intervention period in order to reduce the risk of bias. In two of the studies, the outcome assessors were blinded to treatment assignment. In three studies, the outcome measure was described in a reliable way.
Table 3. Results of critical appraisal of included studies
Qualitative synthesis
Instrument: In all of the studies the validated Persian version of the STAI was utilized as the outcome measure.
Quran recitation: In all of the studies except three [36, 42, 43], the Quran recitation was played for a duration of 20 minutes. The chapters (Surahs) Yusuf (Joseph) and Ar-Rahman (The Compassionate) were the most commonly used sections, and these were used in three studies. Most of the studies had two patient groups (intervention and control) but three studies included two interventions (one Quran recitation and the other music) with one control group. In these studies, 20 minutes of relaxing music was played to the second patient group.
Anxiety: In all of the studies, Quran recitation significantly reduced the level of anxiety in the intervention group. In the three studies that measured the effect of both music and Quran recitation as interventions, it was revealed that the impact of Quran recitation was larger than that of the music [30, 38, 41]. Four studies evaluated the levels of trait and state anxiety separately [36, 39, 42, 43]. These studies showed a significant decrease in both the trait anxiety and state anxiety in intervention group. One study reported just the total anxiety level [44].
Vital signs and pain: Four studies evaluated the impact of Quran recitation and music on patients’ vital signs [30, 31, 42, 44]. The results of Mirbagher et al. and Sharafi show that Quran recitation had a significant effect on patients’ breathing, blood pressure and pulse rate [30, 44]. The study of Tayebi et al. showed a significant reduction in breathing and blood pressure but no significant reduction in pulse rate [42]. The results of Shafiei's study were in contradiction with those of Tayebi et al. in that breathing and blood pressure exhibited no significant changes while pulse rate reduced significantly after intervention [31]. Conversely, Asgari’s study showed a significant pain reduction in patients undergoing abdominal surgeries [37].
Quantitative synthesis
In this review 9 studies were included comprising a total of 652 patients with elective surgeries who were pooled in the meta-analysis. Three studies were excluded from meta-analysis because the SD was not reported for the mean anxiety score [43, 45] or only the total state and trait anxiety score was reported [44]. The intervention group was formed of 336 patients who listened to between 15 and 20 minutes of Quran recitation.
The mean anxiety score before and after intervention was used to calculate the pooled effect size. According to the results of the meta-analysis, Quran recitation had a positive effect on reducing anxiety in elective surgeries. Since the heterogeneity among included studies was statistically significant (Q=23.05, I2=65.29, P=0.003), a random effects model was used to calculate the pooled effect size. The pooled difference in means calculated using a random effects model for anxiety showed a statistically significant decrease in anxiety for the Quran recitation group (difference in means: −8.893; 95% CI: −10.763 to −7.022; P < 0.001). Figure 2 shows the forest plot of the combined effect size. Subgroup analysis was performed based on the type of surgery which was categorized into minor and major surgical procedures. The definition of minor and major surgical procedures was based on prior literature [46]. Major surgeries included abdominal surgeries, elective general surgeries and cesarean section. Minor surgeries included endoscopy, angiography and cardiac catheterization. The subgroup analysis showed that Quran recitation has a beneficial effect on reducing anxiety in both major surgical procedures (difference in means: −8.327; 95% CI: −11.005 to −5.649; P < 0.001) and minor surgical procedures (difference in means: −9.877; 95% CI: −12.808 to −6.946; P < 0.001) (Figure 3).
According to the funnel plot and the Egger regression test (Figure 4), there was no publication bias (intercept=-1.64, 95% CI: -5.94 to 2.64, t=0.907, df=7, P=0.39).