**7. Ventilation tube insertion (VTI) for OME**

Previous studies have shown that 90% or more of the children who undergo palatoplasty for CLP still suffer recurrent OME [20], which is a reflection of persistent poor Eustachian tube function after repair surgery [47]. Thus, many doctors prefer to perform the repair of cleft palate and ventilation tube surgery simultaneously when the child is 1 year old [2, 17, 48–50]. This combined surgical approach is done in the hope of overcoming the problem of middle ear effusion and improving the hearing ability of children, thereby enhancing their long‐term linguistic development.

This chapter summarizes previous studies that addressed the effectiveness of VTI for OME in CLP children aged 18 years or less. Each of the studies we summarize below measured outcomes using a variety of methods. We attempted to normalize those measurements. As for hearing outcomes, the natural effect measure refers to the difference in hearing ability. For studies using outcome measures on different scales, we summarized the findings as the percentage of ears presenting hearing loss or improvement. For the frequency of grommet insertion, measurements were summarized as the percentages of ears that underwent one or more grommet insertions and the number of times that insertion was performed. For com‐ plications or sequelae, the main summary measure was the occurrence of complications. For middle ear status, the effect measures included the rates of OME recurrence and resolution and the percentage of ears presenting various types of tympanogram.

#### **7.1. Comparative effectiveness for hearing outcome**

#### *7.1.1. CLP children versus age‐matched non‐CLP children*

Two studies compared CLP children with age‐matched healthy children with regard to hear‐ ing outcomes after VTI for OME [51, 52]. One prospective study with an excellent study design reported similar hearing outcomes between children with and without palate condi‐ tions (CLP group 10.5 dB versus control group 10.9 dB, p > 0.05, follow‐up 5–7 years) over the short term [51]. The other retrospective study of moderate study design reported a signifi‐ cantly higher percentage of ears with hearing loss (CLP group 24% versus control group 0%, follow‐up 3–5 years) [52]. However, 64% of children in the CLP group underwent VTI, while only 6% in the non‐CLP group underwent VTI (p < 0.0005).

#### *7.1.2. Pre‐VTI versus post‐VTI hearing outcomes*

Hearing outcomes were evaluated in several case‐series studies [16, 23, 43, 53–57]. Over the long term, between 50 and 94% of CLP children recovered normal hearing after being administered VTI in conjunction with palatoplasty (follow‐up 5.5–15.4 years) [16, 43, 54–57]. Furthermore, children requiring a higher number of VTIs were at increased significant risk for long‐standing hearing loss [16, 23].

#### *7.1.3. VTI versus non‐VTI*

Zheng et al. conducted a randomized controlled trial to determine the effectiveness of grom‐ mets on hearing recovery among CLP children with OME [58]. The authors reported hear‐ ing improvement in only 22 of 39 CLP children with VTI; however, no hearing results were obtained from those that did not undergo VTI. Furthermore, the authors reported hearing outcomes over the short term (6 months of observation); however, little emphasis was placed on the long‐term outcomes, which makes it difficult to interpret their results.

Several prospective [51, 59, 60] and retrospective [20, 44, 46, 52, 61–68] cohort studies evaluated hearing outcomes. Among these cohort studies, several studies compared VTI with non‐VTI (i.e., myringotomy alone, hearing aids, watchful waiting) [44, 60, 62, 64–68]. It has been reported that the improvements in hearing afforded by VTI over the short term (within 18 months after VTI) are more pronounced than those of myringotomy, watchful waiting, or HA [64–66]. Potsic et al. found that, compared with CLP children without VTI for OME, those with VTI had a lower percentage of ears presenting hearing loss over the short term (less than 5 years) [68]. As for long‐term hearing outcomes, Hubbard et al. reported that early VTI (3 month of age) could have a greater effect on hearing than that achieved when adopting a conservative approach to treatment [60].

Despite the fact that most studies on hearing outcomes have advocated VTI for CLP chil‐ dren, a number of researchers have expressed reservations, based on conflicting results. Some cohort studies observed that CLP children that had undergone VTI for OME presented worse hearing outcomes over the short term (less than 5 years) [44] or a higher percentage of ears with hearing loss after surgery over the long term (9–21 years), compared to children that did not undergo the procedure [62, 67].

#### *7.1.4. Summary of evidence on hearing outcome*

More than half (50–94%) of CLP children recovered normal hearing 5–15 years after VTI [16, 43, 54–57]. Moreover, compared with conservative management, most studies have shown that VTI is beneficial to hearing recovery over the short as well as long term [60, 64– 66, 68]. There remains a belief that early VTI at the time of palatoplasty is beneficial; however [69], there is little evidence indicating the optimal timing for grommet insertion.

#### **7.2. Comparative effectiveness for speech and language outcomes**

#### *7.2.1. CLP children versus age‐ and sex‐matched non‐CLP control*

One article compared CLP children with age‐ and sex‐matched non‐CLP controls with regard to post‐VTI speech and language outcomes [69]. Normal or near‐normal speech intelligibility ratings were similar in CLP (90%) and non‐CLP children (96%).

#### *7.2.2. VTI versus non‐VTI*

This chapter summarizes previous studies that addressed the effectiveness of VTI for OME in CLP children aged 18 years or less. Each of the studies we summarize below measured outcomes using a variety of methods. We attempted to normalize those measurements. As for hearing outcomes, the natural effect measure refers to the difference in hearing ability. For studies using outcome measures on different scales, we summarized the findings as the percentage of ears presenting hearing loss or improvement. For the frequency of grommet insertion, measurements were summarized as the percentages of ears that underwent one or more grommet insertions and the number of times that insertion was performed. For com‐ plications or sequelae, the main summary measure was the occurrence of complications. For middle ear status, the effect measures included the rates of OME recurrence and resolution

Two studies compared CLP children with age‐matched healthy children with regard to hear‐ ing outcomes after VTI for OME [51, 52]. One prospective study with an excellent study design reported similar hearing outcomes between children with and without palate condi‐ tions (CLP group 10.5 dB versus control group 10.9 dB, p > 0.05, follow‐up 5–7 years) over the short term [51]. The other retrospective study of moderate study design reported a signifi‐ cantly higher percentage of ears with hearing loss (CLP group 24% versus control group 0%, follow‐up 3–5 years) [52]. However, 64% of children in the CLP group underwent VTI, while

Hearing outcomes were evaluated in several case‐series studies [16, 23, 43, 53–57]. Over the long term, between 50 and 94% of CLP children recovered normal hearing after being administered VTI in conjunction with palatoplasty (follow‐up 5.5–15.4 years) [16, 43, 54–57]. Furthermore, children requiring a higher number of VTIs were at increased significant risk for

Zheng et al. conducted a randomized controlled trial to determine the effectiveness of grom‐ mets on hearing recovery among CLP children with OME [58]. The authors reported hear‐ ing improvement in only 22 of 39 CLP children with VTI; however, no hearing results were obtained from those that did not undergo VTI. Furthermore, the authors reported hearing outcomes over the short term (6 months of observation); however, little emphasis was placed

Several prospective [51, 59, 60] and retrospective [20, 44, 46, 52, 61–68] cohort studies evaluated hearing outcomes. Among these cohort studies, several studies compared VTI with non‐VTI (i.e., myringotomy alone, hearing aids, watchful waiting) [44, 60, 62, 64–68]. It has been reported that the improvements in hearing afforded by VTI over the short term (within 18 months after VTI)

on the long‐term outcomes, which makes it difficult to interpret their results.

and the percentage of ears presenting various types of tympanogram.

**7.1. Comparative effectiveness for hearing outcome** *7.1.1. CLP children versus age‐matched non‐CLP children*

102 Designing Strategies for Cleft Lip and Palate Care

only 6% in the non‐CLP group underwent VTI (p < 0.0005).

*7.1.2. Pre‐VTI versus post‐VTI hearing outcomes*

long‐standing hearing loss [16, 23].

*7.1.3. VTI versus non‐VTI*

Several studies have assessed speech and language outcomes in CLP patients with OME, including prospective [60] and retrospective cohort studies [44, 69–72]. Five articles compared children that were or were not administered VTI for OME [44, 60, 70–72]. No differences in speech or language development were observed in short‐term (0–5 years) [44, 72] or long‐term (8–10 years) [70, 71] follow‐ups. With one exception, all investigators used the same number of CLP children matched for cleft type, age, sex, socioeconomic status, and birth order. After a 9‐year follow‐up, consonant articulation was found to be better after early VTI (p = 0.03) [60]. However, the authors performed myringotomy on the control group (when deemed neces‐ sary), which prevented the clear elucidation of differences in functional outcome between children that did or did not undergo VTI for OME.

#### *7.2.3. Summary of evidence on speech and language outcomes*

No differences in speech or language development were observed between CLP children that underwent conservative observation and those that underwent aggressive VTI, over the short term (0–5 years) [44, 72] or long term (8–10 years) [70, 71]. Further, assessments of speech by Merrick et al. revealed a similar percentage of children with normal or near‐normal speech intelligibility ratings in the CLP and non‐CLP groups [69]. These findings appear to indicate that speech and language skills do not depend on the VTI approach to OME treatment, but rather on the timing of palatoplasty.

#### **7.3. Complications of VTI for OME**

#### *7.3.1. CLP children versus age‐matched healthy children*

Two studies compared age‐matched healthy control children with regard to VTI complica‐ tions [51, 52]. One study showed that the prognosis of children with CLP that undergo early VTI is comparable to that of children without CLP [51]; however, the other study reported contradictory results with higher rates of complications among CLP children [52].

#### *7.3.2. VTI versus non‐VTI*

Several retrospective cohort studies compared children with and without VTI (i.e., hearing aids or watchful waiting) with regard to post‐VTI complications [44, 46, 61, 62, 66, 67, 72]. Those studies reported higher complication rates among children with VTI than among those without, over the short term (<5 years of follow‐up) [44, 46, 61, 66, 72] as well as long term (9–21 years of observation) [62, 67]. All results were statistically significant; however, differ‐ ences were not calculated in two of the studies [62, 72].

Among the various types of complications, tympanosclerosis and otorrhea generally present transient but common sequelae following VTI [73, 74], with other studies reported permanent perforations and cholesteatoma [73, 75, 76]. As for the occlusion of grommets, infection, and the presence of granulation tissue, the evidence was too limited and blurred to determine the direction of effects between VTI and adverse events in CLP children with OME.

#### *7.3.3. Tympanosclerosis*

Tympanosclerosis has little influence on hearing [16, 72, 77]; however, this is the most com‐ mon VTI‐related complication, the rates of which were in the range of 0–52% [4, 20, 44, 46, 52–54, 57, 58, 61, 65, 67, 72, 78]. Tympanosclerosis can, albeit rarely, cause conductive hearing loss if it extensively involves the ossicle chain [72].

#### *7.3.4. Otorrhea*

Otorrhea is a complication of the tympanostomy tubes in children who are otherwise healthy [79]. However, otorrhea has not been systematically studied in CLP children after VTI. Some studies have reported a low probability (4–11.5%) of post‐VTI otorrhea in CLP children [44, 50, 66, 79], whereas others reported inconsistent results (55–68%) [31, 57, 78]. The evidence is inconclusive due to conflicting results among these studies. Otorrhea appeared to be more common in ears that underwent VTI than in those that did not [66]. However, the evidence is insufficient to reveal an association between the long‐term use of grommets and otorrhea. Only one study on post‐VTI otorrhea reported the management of otorrhea [72]. Freeland et al. found that although 68% of infants developed otorrhea following the use of grommets over a mean duration of 3.9 months, the otorrhea usually responded promptly to antibiotic‐corticoste‐ roid drops or systemic antibiotic treatment in more resistant cases.

#### *7.3.5. Eardrum perforation*

term (0–5 years) [44, 72] or long term (8–10 years) [70, 71]. Further, assessments of speech by Merrick et al. revealed a similar percentage of children with normal or near‐normal speech intelligibility ratings in the CLP and non‐CLP groups [69]. These findings appear to indicate that speech and language skills do not depend on the VTI approach to OME treatment, but

Two studies compared age‐matched healthy control children with regard to VTI complica‐ tions [51, 52]. One study showed that the prognosis of children with CLP that undergo early VTI is comparable to that of children without CLP [51]; however, the other study reported

Several retrospective cohort studies compared children with and without VTI (i.e., hearing aids or watchful waiting) with regard to post‐VTI complications [44, 46, 61, 62, 66, 67, 72]. Those studies reported higher complication rates among children with VTI than among those without, over the short term (<5 years of follow‐up) [44, 46, 61, 66, 72] as well as long term (9–21 years of observation) [62, 67]. All results were statistically significant; however, differ‐

Among the various types of complications, tympanosclerosis and otorrhea generally present transient but common sequelae following VTI [73, 74], with other studies reported permanent perforations and cholesteatoma [73, 75, 76]. As for the occlusion of grommets, infection, and the presence of granulation tissue, the evidence was too limited and blurred to determine the

Tympanosclerosis has little influence on hearing [16, 72, 77]; however, this is the most com‐ mon VTI‐related complication, the rates of which were in the range of 0–52% [4, 20, 44, 46, 52–54, 57, 58, 61, 65, 67, 72, 78]. Tympanosclerosis can, albeit rarely, cause conductive hearing

Otorrhea is a complication of the tympanostomy tubes in children who are otherwise healthy [79]. However, otorrhea has not been systematically studied in CLP children after VTI. Some studies have reported a low probability (4–11.5%) of post‐VTI otorrhea in CLP children [44, 50, 66, 79], whereas others reported inconsistent results (55–68%) [31, 57, 78]. The evidence is inconclusive due to conflicting results among these studies. Otorrhea appeared to be more common in ears that underwent VTI than in those that did not [66]. However, the evidence is insufficient to reveal an association between the long‐term use of grommets and otorrhea. Only one study on post‐VTI otorrhea reported the management of otorrhea [72]. Freeland et al.

direction of effects between VTI and adverse events in CLP children with OME.

contradictory results with higher rates of complications among CLP children [52].

rather on the timing of palatoplasty.

104 Designing Strategies for Cleft Lip and Palate Care

**7.3. Complications of VTI for OME**

*7.3.2. VTI versus non‐VTI*

*7.3.3. Tympanosclerosis*

*7.3.4. Otorrhea*

*7.3.1. CLP children versus age‐matched healthy children*

ences were not calculated in two of the studies [62, 72].

loss if it extensively involves the ossicle chain [72].

In CPL children, eardrum perforation occurred in 0–19% of VT‐treated ears in follow‐ups of 1–15 years [4, 16, 20, 43, 44, 46, 50–54, 56–58, 60, 61, 66, 67, 70, 72, 78]. In a study by Shapiro, the rate of eardrum perforation was found to be as high as 50% after VTI [80]; however, the num‐ ber of children with VTI (only six children) was too small to be of reference value (low‐quality study design). In contrast, eardrum perforation was observed in only 0–7% of non‐VT‐treated ears (i.e., observation or hearing aids) during follow‐ups of 1–4 years [61, 66, 72]. In non‐CLP children with OME, only one study reported a 3% incidence of post‐VTI eardrum perforation within a 5‐year follow‐up [51].

#### *7.3.6. Cholesteatoma*

Grommet insertion has been reported to be an iatrogenic cause of secondary acquired choles‐ teatoma [81–86]. The development of the disease is quite uncommon, with a reported rate of approximately 1% in non‐CLP children with VTI [73, 87]. However, evidence has shown that the CLP children were at increased risk of developing cholesteatoma [66, 73], with a higher rate of 0–6.9% within 12 years after VTI [16, 23, 58, 62, 66, 67, 73, 80, 88].

It should be noted that Hornigold et al. reported an incidence of 29% for CLP children 21 years after VTI for OME [62], Similarly, Spilsbury et al. conducted a retrospective cohort study on the relationship between CLP and secondary cholesteatoma following VTI in children [73]. They examined the complete hospital in‐patient history of a large unselected population (869 CLP children versus 56080 non‐CLP children) over a 29‐year period. The authors reported that children with CLP developed cholesteatoma 7.5 (95% confidence interval, 3.8–18.2) times faster after the first VTI, compared to children without CLP.

#### *7.3.7. Summary of evidence on VTI complications*

CLP children with VTI generally have a higher risk of complications than do those without, over the short‐term (less than 5 years) [44, 46, 61, 66, 72] as well as long‐term (9–21 years) follow‐up [62, 67]. However, compared to non‐CLP children with OME, there is insufficient evidence to draw any conclusions due to conflicting results among these studies on CLP and non‐CLP children [51, 52].

#### **7.4. Comparative effectiveness for middle ear status**

Previous studies have compared the effect of VTI on middle ear by using outcome measure‐ ments including the rates of OME resolution, persistent OME, and OME recurrence. The rates of OME resolution were reported in three high‐quality studies, including a randomized control trial, a prospective cohort study, and a retrospective cohort study [50, 51, 58]. The rates of OME resolution ranged from 48.7 to 86% within the first 6.5 years. These results were supported by Goudy et al., who reported a median resolution time of conductive hearing loss of approximately 5 years [23]. Kuscu et al. observed that normal otoscopic examination find‐ ings were higher in CLP children without VTI than in those with VTI [89].

Persistent OME was observed in 29–52% of CLP children 4–7 years after VTI [20, 44, 68, 72]. Gordon et al. [67] found that only 5% of CLP children had persistent OME 9 years or more after palatoplasty with VTI, concluding that Eustachian tube function may be adequate by age of 9 years. These results are supported by Smith et al. [43], who found that Eustachian tube function eventually returned to normal in most CLP children and that the age of Eustachian tube normalization was approximately 8 years (1.5–17.3). As for OME recurrence, a number of studies have reported that 17–45% of CLP children had OME recurrence 3–6 years after VTI, at a mean age of approximately 7 years [20, 56, 57, 61].

#### *7.4.1. CLP children versus non‐CLP control*

Four articles reported in post‐VTI middle ear function in CLP and non‐CLP children [51, 52, 59, 69], three of which included an age‐matched non‐CLP control group [51, 52, 69]. The results in studies by Ovesen and Blegvad‐Andersen [52] and Broen et al. [59] were not con‐ sidered for further interpretation because only 6 and 31% of the non‐CLP children with OME underwent VTI, respectively. Merrick et al. reported comparable rates of persistent OME in children with and without cleft palate (24% versus 14%, p = 0.31) [69]. Valtonen et al. reported similar OME resolution rates in CLP and non‐CLP children (64.1% versus 60.6%) [51]. In sum‐ mary, the prognosis for middle ear recovery among CLP children with early VTI is compa‐ rable to that of children without CLP.

#### *7.4.2. VTI versus non‐VTI*

Zheng et al. performed a randomized controlled trial comparing OME resolution rates between CLP children with and without VTI [58]. They reported a significantly higher OME resolution rate (48.7%) in children undergoing palatoplasty and VTI than in those undergo‐ ing palatoplasty alone (24.5%, p < 0.01). Children with VTI had a shorter observation period (6 months versus 20 months); however, the authors expected that the OME resolution rate would have been higher if the children had been followed up for the same period as those without VTI, such that the difference in resolution rate between the groups would become increasingly pronounced. In another study by Potsic et al., [68] the authors found that CLP children that did not undergo VTI had a significantly higher rate of persistent OME at the age of 5 years than did those with VTI. Freeland et al. [72] obtained the same result for CLP children at the age of 4 years. However, two other studies reported conflicting results, i.e., a higher rate of persistent OME in CLP children with VTI [44, 67].

#### *7.4.3. Summary of evidence on middle ear status*

Three high‐quality studies reported that more than half (48.7–86%) of the CLP children that underwent VTI presented OME resolution within the first 6.5 years [50, 51, 58]. The median resolution time of conductive hearing loss was found to be approximately 5 years [23]. The high OME resolution rates were supported by four other studies, in which persistent OME was observed in less than half (29–52%) of the CLP children in the first 4–7 years after VTI [20, 44, 68, 72]. Eustachian tube function began to normalize by 7–9 years of age [20, 43, 44, 50, 51, 58, 67, 68, 72]. In addition, fewer than half of the CLP children (17–45%) presented OME recurrence within the first 3–6 years of follow‐up [20, 56, 57, 61]. Importantly, the prognosis for CLP children that undergo early VTI was comparable to that of the children without CLP.

#### **7.5. Frequency of grommet insertion**

supported by Goudy et al., who reported a median resolution time of conductive hearing loss of approximately 5 years [23]. Kuscu et al. observed that normal otoscopic examination find‐

Persistent OME was observed in 29–52% of CLP children 4–7 years after VTI [20, 44, 68, 72]. Gordon et al. [67] found that only 5% of CLP children had persistent OME 9 years or more after palatoplasty with VTI, concluding that Eustachian tube function may be adequate by age of 9 years. These results are supported by Smith et al. [43], who found that Eustachian tube function eventually returned to normal in most CLP children and that the age of Eustachian tube normalization was approximately 8 years (1.5–17.3). As for OME recurrence, a number of studies have reported that 17–45% of CLP children had OME recurrence 3–6 years after VTI,

Four articles reported in post‐VTI middle ear function in CLP and non‐CLP children [51, 52, 59, 69], three of which included an age‐matched non‐CLP control group [51, 52, 69]. The results in studies by Ovesen and Blegvad‐Andersen [52] and Broen et al. [59] were not con‐ sidered for further interpretation because only 6 and 31% of the non‐CLP children with OME underwent VTI, respectively. Merrick et al. reported comparable rates of persistent OME in children with and without cleft palate (24% versus 14%, p = 0.31) [69]. Valtonen et al. reported similar OME resolution rates in CLP and non‐CLP children (64.1% versus 60.6%) [51]. In sum‐ mary, the prognosis for middle ear recovery among CLP children with early VTI is compa‐

Zheng et al. performed a randomized controlled trial comparing OME resolution rates between CLP children with and without VTI [58]. They reported a significantly higher OME resolution rate (48.7%) in children undergoing palatoplasty and VTI than in those undergo‐ ing palatoplasty alone (24.5%, p < 0.01). Children with VTI had a shorter observation period (6 months versus 20 months); however, the authors expected that the OME resolution rate would have been higher if the children had been followed up for the same period as those without VTI, such that the difference in resolution rate between the groups would become increasingly pronounced. In another study by Potsic et al., [68] the authors found that CLP children that did not undergo VTI had a significantly higher rate of persistent OME at the age of 5 years than did those with VTI. Freeland et al. [72] obtained the same result for CLP children at the age of 4 years. However, two other studies reported conflicting results, i.e., a

Three high‐quality studies reported that more than half (48.7–86%) of the CLP children that underwent VTI presented OME resolution within the first 6.5 years [50, 51, 58]. The median resolution time of conductive hearing loss was found to be approximately 5 years [23]. The high OME resolution rates were supported by four other studies, in which persistent OME

ings were higher in CLP children without VTI than in those with VTI [89].

at a mean age of approximately 7 years [20, 56, 57, 61].

higher rate of persistent OME in CLP children with VTI [44, 67].

*7.4.3. Summary of evidence on middle ear status*

*7.4.1. CLP children versus non‐CLP control*

106 Designing Strategies for Cleft Lip and Palate Care

rable to that of children without CLP.

*7.4.2. VTI versus non‐VTI*

A significant proportion (53.2–98%) of CLP children with OME required VTI [4, 51, 54, 61, 78] with an average of between 0.55 and 2.2 VTIs per patient in the first 7 years of observation [20, 44, 59, 66]. Cleft defects play an important role in OME formation; therefore, it would be reasonable to assume a higher need for grommets in children with more overt palatal mal‐ formations. This assumption is supported by several studies [67, 71, 88], in which a relation‐ ship was established between the degree of clefting and the frequency of VTI, with severe or complete clefts more likely to involve grommet insertion. Children with cleft palate had a sig‐ nificantly higher frequency of VTIs than those without [51, 59]. However, this issue requires further investigation. Lithovius et al. reported that the severity of the cleft was not a signifi‐ cant factor related to the number of ventilation tubes required [90]. Surgical techniques used to repair the cleft palate are not significantly associated with the number of VTI required [90]; however, palatoplasty may indeed decrease the rate of ventilation tube reinsertion in children with cleft palate, as evidenced by a recent population‐based study [91].

#### **7.6. Summary of evidence pertaining to effectiveness of VTI for OME**

Compared with a conservative approach, early VTI was shown to improve hearing, and this improvement was maintained in more than half of the CLP children 5–15 years after surgery. Nonetheless, VTI does not necessarily lead to improvements in speech or language development in CLP children, and the CLP children with VTI had a higher risk of complica‐ tions than did those without. It appears that VTI is beneficial for the recovery from OME in CLP patients. There is insufficient evidence to suggest the optimal timing of VTI (e.g., at the time of repair of lip/palate); however, it may be convenient for surgeons to combine these procedures.

#### **7.7. Limitations of previous studies**

Despite considerable research into subgroups of CLP children with regard to the effective‐ ness of grommets for OME, heterogeneity in the design of studies has proven a formidable barrier to the synthesis of evidence [92, 93]. Most previous studies failed to clearly describe their criteria in the definition of OME. Previous studies included subjects of different ages with different types of cleft who had undergone different procedures and employed different criteria for VTI. Grommet insertion (unilateral or bilateral) was treated as a single procedure in some studies or as two procedures in other studies. The measures used in the studies were nonuniform; different time points were used for the determination of outcomes, and baseline measures were not always provided. Studies also varied in the length of observation periods. Most studies in this review were retrospective studies. Only otologic findings during a par‐ ticular month, or interpolation from examinations in adjoining months, were used in arriving at the monthly status of each ear. Thus, patient history was of limited value because it was difficult to determine when grommets had been extruded and if ear drainage was occurring. Due to mixed results, statistical differences could not be calculated for each complication, such that it is unclear whether the differences reached statistical significance. Finally, the issue of missing data was not taken into account.
