Healthcare and economic burden of anticholinergic use in adults with overactive bladder: a systematic literature review

Overall, 11 of the 34 articles reported data on inpatient hospitalizations (Table 3 & Supplementary Table 4). Across all studies, the proportion of patients requiring hospitalization ranged from 0 to 5% for OAB-related hospitalizations [46,56,57] and 9.9 to 49.0% for all-cause hospitalizations [43,46,49,60].

Three studies included a comparator arm with patients who were not treated with anticholinergic medications; however, comparators differed between studies [45,59,60]. A claims analysis by Yehoshua et al. reported that patients who experienced OAB with incontinence (i.e., OAB wet) and received anticholinergic medications experienced significantly more yearly all-cause hospitalizations (0.301) compared with patients without OAB (0.235; p = 0.001) [60]. A claims analysis by Hall et al. reported no differences in monthly hospitalizations in patients receiving tolterodine or oxybutynin versus patients with OAB who did not receive pharmacotherapy [45]. In a 2021 claims analysis by Walker et al., no significant difference in inpatient visits was shown among frail patients with OAB receiving anticholinergic medications or a β₃-receptor agonist (both groups had a median of 0 monthly inpatient visits) [59].

The remaining 8 studies did not include nonanticholinergic comparators but instead assessed anticholinergic medication burden [50], medication persistence [46] and anticholinergic medication [48,49,58] or patient [43,56,57] characteristics. Anticholinergic burden was assessed by one study, a claims analysis by Lozano-Ortega et al. [50], which estimated the impact of falls/fractures on HCRU and costs according to levels of anticholinergic burden among individuals with OAB. HCRU and costs were compared before and after a fracture and the anticholinergic burden measure [64] was used to calculate anticholinergic burden as a unitless score, accounting for dose and potency. It showed that medium to high anticholinergic burden (score ≥90 on the cumulative anticholinergic burden measure) was associated with a greater mean number of hospitalizations per 100 person-years than no to low anticholinergic burden (score <90) [50]. Persistence with anticholinergic medications was also assessed by one study, a claims analysis by Ivanova et al., which found that patients with OAB who switched from one anticholinergic medication to another had significantly higher rates of hospitalization in the following 6 months than those who persisted with or discontinued an anticholinergic medication [46].

Three studies assessed hospitalizations according to anticholinergic medication characteristics. A claims analysis by Kachru et al. found that patients using nonselective anticholinergic medications, which have an affinity for muscarinic receptors M1–M5 (oxybutynin, fesoterodine, tolterodine, trospium), experienced a higher all-cause hospitalization rate over the 6 months after initiation than patients using selective anticholinergic medications, which have a high affinity for the M3 muscarinic receptors that are responsible for bladder contraction (solifenacin, darifenacin; 24.14 vs 21.58%, respectively; p = 0.0007) [49]. Jumadilova et al. assessed inpatient hospitalizations, categorized as those related to UTI or depression or unrelated to OAB, among patients with OAB taking tolterodine extended release (ER), oxybutynin ER or oxybutynin immediate release (IR) [48]. It was found that patients taking tolterodine ER experienced fewer yearly UTI-related hospitalizations than patients taking oxybutynin ER or IR, fewer yearly depression-related hospitalizations versus oxybutynin ER but not versus oxybutynin IR and fewer yearly OAB-unrelated hospitalizations versus oxybutynin IR but not versus oxybutynin ER [48]. In contrast, a 2005 claims analysis by Varadharajan et al. found no significant differences in total OAB-related inpatient hospitalizations among patients taking tolterodine ER versus oxybutynin ER or IR [58].

Three studies assessed hospitalizations in patients with OAB taking anticholinergic medications according to patient characteristics. A claims analysis by Balkrishnan et al. found that patients who were enrolled in a Health Maintenance Organization (HMO) health plan for 1 to 3 years and continuously on anticholinergic medications experienced a numeric increase in the rate of hospitalizations over time, with 23, 24 and 28% of patients in years 1, 2 and 3, respectively, having experienced a hospitalization in the previous year [43]. Two analyses by Tang et al. compared hospitalizations between patients with OAB [56] or neurogenic detrusor overactivity [57] with or without incontinence; no significant difference was found in the 12-month rate of OAB-related hospitalizations between patients in the USA with OAB or neurogenic detrusor overactivity, with or without urinary incontinence.

Nine studies reported data on outpatient visits, with variation between studies on the type of outpatient visits (i.e., physician visits and emergency department visits). Across all studies, the percentage of patients with ≥1 OAB-related outpatient visit ranged from 20.3 to 100%; however, observation periods varied from 1 month to 1 year. An analysis by Ju et al. used the National Ambulatory Medical Care Survey database to estimate the prevalence of outpatient visits associated with an anticholinergic medication to treat OAB among adult female patients in the USA and found that women actively taking anticholinergic medications for OAB had 8.1 million outpatient visits in 2009, accounting for 1.6% of all outpatient visits in the USA [47].

Two studies included a comparator arm with patients who were not treated with anticholinergic medications; however, comparators differed between studies. Yehoshua et al. reported that patients with OAB wet and receiving an anticholinergic medication had more yearly outpatient visits per patient than those without OAB (16.96 vs 11.25, respectively) [60]. Similarly, Hall et al. reported 0.21 to 0.23 monthly outpatient hospitalizations in patients with OAB taking an anticholinergic medication compared with 0.18 monthly outpatient hospitalizations in patients not receiving any drug treatment for OAB; however, no statistical comparisons were made [45].

The remaining studies did not include nonanticholinergic comparators. They instead stratified by medication persistence [46], anticholinergic medication burden [37,50] and reason for outpatient visit [48,58].

Ivanova et al. was the only study to assess the effect of anticholinergic medication persistence on outpatient visits. Patients with OAB who switched from 1 anticholinergic medication to another had a greater mean number of all-cause and OAB-related outpatient visits in the 6 months following switching than patients who persisted with an anticholinergic medication and had more outpatient visits than patients who discontinued an anticholinergic medication [46].

Two studies assessed the effect of anticholinergic burden on outpatient visits. Lozano-Ortega et al. found that medium to high anticholinergic burden was associated with a greater mean number of outpatient visits per 100 person-years than no to low anticholinergic burden [50]. In the course of developing a budget impact model, Perk et al. [37] performed a retrospective medical record analysis to assess the relationship between the 6-point anticholinergic cognitive burden (ACB) scale score [65] and outpatient visits in adults ≥65 years. Consistent with results from Lozano-Ortega et al., Perk et al. estimated a mean increase of 1.14 annual outpatient visits per unit increase in ACB score.

Two studies reported annual outpatient visits by reason for visit among patients with OAB and an anticholinergic medication claim. Jumadilova et al. found that, depending on the specific anticholinergic agent used, patients had 0.16 to 0.26 outpatient management visits related to UTIs, 0.55 to 0.59 outpatient management visits related to depression and 12.25 to 12.86 outpatient management visits related to non-OAB causes per year [48]. Varadharajan et al. found that patients with OAB and an anticholinergic medication claim had 0.46 to 0.53 outpatient management visits related to OAB and 12.99 to 13.8 outpatient management visits related to other causes per year [58].

Six studies reported data on physician visits; however, only 1 study included a comparator arm with patients who were not treated with an anticholinergic medication. Hall et al. found that patients with OAB and taking anticholinergic medications experienced a numerically greater mean number of physician visits per month than patients with OAB who were not receiving pharmacologic treatment (1.26–1.51 with treatment vs 1.17 without treatment) [45]. A single study assessed the relationship between physician visits and anticholinergic burden; Lozano-Ortega et al. found that patients with OAB with medium to high anticholinergic burden had a greater mean number of general practitioner visits than patients with no to low anticholinergic burden [50]. Two studies by Tang et al. assessed the relationship between continence and physician visits, finding similar numbers of physician visits related to OAB or neurogenic detrusor overactivity in patients with versus without urinary incontinence taking anticholinergic medications [56,57]. Two studies by Zinner et al. assessed the relationship between anticholinergic medication and physician visits, finding that patients in the VESIcare Efficacy and Research Study US (VERSUS) trial had fewer nonprotocol-related office visits after switching from tolterodine to solifenacin [61,62].

Eight studies reported data on emergency department visits. Across all studies reporting emergency department visits, 15.9 to 46.9% of anticholinergic-treated patients with OAB required ≥1 emergency department visit per year, with a yearly average of 0.96 to 1.92 emergency department visits per patient. Two studies included a comparator arm with patients with OAB not treated with anticholinergic medications [45,60]; the remainder stratified by anticholinergic burden [37,50], medication persistence [46] and medication [48,58] or patient characteristics [43].

Two studies included a comparator arm of patients not treated with anticholinergic medications, but comparators differed between studies. Yehoshua et al. found that patients with OAB wet taking anticholinergic medications had more annual emergency department visits than those without OAB (1.92 vs 1.41, respectively) [60]. In contrast, Hall et al. found no difference in annual emergency department visits among patients taking tolterodine IR, taking oxybutynin or receiving no pharmacologic treatment (0.03 unadjusted emergency department encounters per patient per month in all groups) [45].

Ivanova et al. was the only study to assess the effect of anticholinergic medication persistence on emergency department visits and reported no differences in OAB-related emergency department visits in the 6 months after switching anticholinergic medications [46].

Two studies assessed the relationship between anticholinergic burden and emergency department visits. Lozano-Ortega et al. reported that patients with OAB and medium to high anticholinergic burden had increased mean emergency department visits compared with those with no to low anticholinergic burden [50]. Similarly, the previously described analysis reported by Perk et al. found that the number of annual emergency department visits increased by 0.114 per unit increase in anticholinergic burden score [37].

The relationship between specific anticholinergic medications and emergency department visits was evaluated in two studies. Jumadilova et al. found that patients receiving tolterodine ER experienced a decrease in frequency of UTI-related emergency department visits and no changes in frequency of depression-related or other OAB-unrelated emergency department visits versus oxybutynin ER or IR [48]. However, Varadharajan et al. found no significant differences between anticholinergic types in OAB-related and non–OAB-related emergency department visits [58].

Balkrishnan et al. assessed the relationship between emergency department visits and patient characteristics. Patients who were enrolled in an HMO health plan for 1 to 3 years and continuously on anticholinergic medications experienced a numeric increase in the rate of emergency department visits over time, with 26, 29 and 30% of patients in years 1, 2 and 3, respectively, having experienced an emergency department visit in the previous year [43].

Total cost estimates were reported in 26 of the 34 studies; metrics included total healthcare (23 studies), total medical (10 studies), total pharmacy (13 studies) and OAB-related condition (2 studies) costs (Table 4 & Supplementary Table 5). Some articles compared patients with and without pharmacologically managed OAB [37,45,52,60], whereas others stratified by adherence [35,36,46], anticholinergic burden or potentially inappropriate anticholinergic prescribing [44,50,53,54,64] or type of OAB medication [29,33,34,37,39–42,51,59].

An analysis conducted by Yehoshua et al. found that patients with OAB wet treated with anticholinergic medications had higher annual healthcare costs ($7562) than those without OAB ($5293) [60]. In a study by Hall et al., patients with OAB who were treated with tolterodine IR or oxybutynin had higher monthly total healthcare costs ($585–$593) than patients with OAB who received no OAB drug treatment ($420) [45]. A study by Pelletier et al. also compared total healthcare costs between patients with OAB receiving anticholinergic medications and patients who received no OAB drug treatment, reporting costs of $9917 and $9657, respectively [52].

Several studies showed that low adherence or persistence led to higher costs among patients taking anticholinergic medications. Ivanova et al. found that patients who switched anticholinergic medications had higher total adjusted all-cause and OAB-related healthcare costs 6 months after index (all cause: $8806; OAB related: $797) than patients who persisted with the original anticholinergic medication (all cause: $7017; OAB related: $642) [46]. A pharmacoeconomic model by Noe et al. also predicted that patients who continued with either tolterodine ER or oxybutynin ER monotherapy would have lower total healthcare costs ($963 and $1040, respectively) than those who discontinued ($1545 and $1539), switched ($1482 or $1491) or added a new anticholinergic medication ($1668 or $1649) [35].

A cost-minimization analysis by Perfetto et al. showed that annual costs for patients taking tolterodine ER or oxybutynin ER increased with greater persistence ($8714–$8766 for patients who discontinued in the first month vs $9136–$9761 for patients who remained on therapy for a year) [36]. The increase in costs was driven by higher pharmacy costs among patients who persisted versus those who discontinued therapy in the first month ($1192–$1217 vs $99–$101, respectively). However, medical costs were lower over time among patients who persisted than among those who discontinued ($7944–$8544 vs $8615–$8665, respectively) [36].

Potentially inappropriate medication (PIM) use of anticholinergics (according to AGS Beers Criteria) and increased anticholinergic medication burden were associated with increased costs. A study by Lozano-Ortega et al. examined the impact of falls/fractures on HCRU and costs according to the level of cumulative anticholinergic burden. Compared with patients who had medium to high anticholinergic burden, patients with no to low anticholinergic medication burden had lower total annual healthcare costs (before fall/fracture, $15,439 vs $24,428; after fall/fracture, $19,463 vs $28,930) and pharmacy costs (before fall/fracture, $2870 vs $6217; after fall/fracture, $3041 vs $6229) [50]. Two studies by Suehs et al. showed that PIM use of anticholinergic medications increased costs among patients with OAB [54,55]. Patients with PIM use of anticholinergic medications according to the 2012 Beers Criteria had total adjusted all-cause healthcare costs of $12,001 per patient per year compared with $9373 for those with non-PIM use [54]. In a follow-up study comparing the 2012 and 2015 Beers Criteria, the 2015 Criteria identified increased PIM use of anticholinergic medications; however, this was found in a younger population with a lower comorbidity burden, resulting in lower total healthcare costs versus the 2012 Criteria (all-cause total healthcare costs: $16,698 based on 2012 Beers Criteria vs $15,016 based on 2015 Beers Criteria; prevalence of PIM use: 20.6 vs 25.0%, respectively) [55].

Pharmacy costs accounted for most OAB-related costs, whereas medical costs – including outpatient and physician visits, hospitalizations and emergency department or intensive care visits – usually accounted for most total healthcare costs [36,38,54,58]. One exception was from a cost–effectiveness model of mirabegron by Wielage et al., which reported that costs were differentially driven by pharmacy costs or medical costs depending on the type of anticholinergic medication and/or the health plan (commercial or Medicare Advantage) [41].

A budget impact model by Perk et al. reported comorbidity costs for patients receiving anticholinergic medications [37]. The model predicted that comorbidity costs (per patient per year) would be higher for patients who did not receive treatment (commercial: $229.78 for prescriptions, $172.95 for medical fees; Medicare Advantage: $150.19 and $113.04, respectively) than for patients receiving anticholinergic medications (commercial: $69.13 for prescriptions, $60.01 for medical fees; Medicare Advantage, $45.18 and $39.22, respectively) [37].

Several studies assessed the costs of anticholinergic medications relative to other approved treatments for OAB, including botulinumtoxin derivatives [33,34,39,42] and a β₃-adrenergic receptor agonist [40,59]. These analyses generally found that anticholinergic medications were not cost-effective compared with other treatments for OAB. One study, a claims analysis by Walker et al., found that frail older adults taking a β₃-adrenergic receptor agonist (mirabegron) had higher total costs than patients taking anticholinergic medications, potentially driven by improved adherence [59].

Seven studies reported on the hospitalization costs of patients taking anticholinergic medications for OAB. However, this included 1 abstract, a claims analysis by Walker et al. that did not identify any inpatient visits in their cohort and thus reported median hospitalization costs of $0 [59]. Of the remaining 6 studies, 3 included a comparator arm comprising patients without pharmacologically managed OAB [38,52,60] and 3 stratified by anticholinergic burden [63], medication adherence [46] or medication type [58].

A claims analysis by Yehoshua et al. reported hospitalization costs of patients with OAB wet relative to a matched cohort of patients without OAB, finding that patients with OAB wet who were treated with anticholinergic medications had significantly higher annual hospitalization costs ($2239) than those without OAB ($1719) [60]. A claims analysis by Pelletier et al. found significantly lower hospitalization costs among patients with OAB who received an anticholinergic medication versus those who were not pharmacologically managed [52]. Similarly, an economic impact model by Qin et al. predicted that patients with OAB treated with fesoterodine would have lower 1-year hospitalization costs than untreated patients [38].

Ivanova et al. was the only study to assess the relationship between adherence to anticholinergic medications and hospitalization costs in patients with OAB, reporting that patients who switched anticholinergic medications had higher all-cause ($2505) and OAB-related ($68) hospitalization costs in the 6 months after switching than patients who persisted with an anticholinergic medication (all cause: $1462; OAB related: $22) or discontinued (all cause: $1744; OAB related: $22) [46].

Lozano-Ortega et al. was the only study to assess the relationship between anticholinergic burden and hospitalization costs in patients with OAB. It showed that patients who experienced falls/fractures and had medium to high anticholinergic burden had higher mean hospitalization costs (prefalls/fractures, $6684; post-falls/fractures, $7943) than patients who experienced falls/fractures and had no to low anticholinergic burden (prefalls/fractures, $3931; post-falls/fractures, $5343) [50].

A claims analysis by Varadharajan et al. assessed hospitalization costs in 2 cohorts of patients with OAB receiving tolterodine ER to matched cohorts receiving either oxybutynin ER or oxybutynin IR; OAB-related hospitalization costs ranged from $78 to $160 per patient per year, whereas non–OAB-related hospitalizations ranged from $2328 to $3720 per patient per year [58]. It found no significant differences in OAB-related hospitalization costs when patients received tolterodine ER versus oxybutynin ER or IR; non–OAB-related related hospitalization costs were significantly lower with tolterodine ER versus oxybutynin IR (p = 0.0148) but not versus oxybutynin ER [58].

Eight studies reported on outpatient visit costs of patients taking anticholinergic medications for OAB. Four studies compared patients with OAB taking anticholinergic medications to patients without pharmacologically managed OAB [37,38,52,60]. The remaining studies focused on anticholinergic burden [50], medication adherence [46] or comparing patients taking different OAB medications [58,59].

A claims analysis by Yehoshua et al. reported outpatient visit costs of patients with OAB wet relative to a matched cohort of patients without OAB, finding that patients with OAB wet who were treated with anticholinergic medications had significantly higher average annual outpatient visit costs ($2326) than those without OAB ($1609) [60]. Pelletier et al. found significantly lower outpatient costs among patients with OAB who were on an anticholinergic medication versus those who were not pharmacologically managed [52]. Similarly, an economic impact model by Qin et al. predicted that patients treated with fesoterodine would have lower 1-year outpatient costs than those with no pharmacologic management [38]. However, a budget impact model by Perk et al. predicted that patients taking anticholinergic medications would have higher anticholinergic medication–related outpatient costs than patients not receiving pharmacologic treatment from both the Medicare Advantage and commercial perspectives, with higher costs for patients on Medicare Advantage versus commercial plans [37].

The claims analysis by Ivanova et al. was the only study to assess the relationship between adherence to anticholinergic medications and hospitalization costs in patients with OAB, reporting that patients who switched anticholinergic medications had higher all-cause and OAB-related outpatient visit costs in the 6 months after switching than patients who persisted with or discontinued an anticholinergic medication [46].

The claims analysis by Lozano-Ortega et al. was the only study to assess the relationship between anticholinergic burden and outpatient visit costs in patients with OAB. It reported that patients with medium to high anticholinergic medication burden who had experienced falls/fractures had higher outpatient visit costs (mean all-cause cost per patient: pre-fall/fracture, $11,526; post-fall/fracture, $14,758) than those with no to low anticholinergic burden (pre-fall/fracture, $8638; post-fall/fracture, $11,079) [50].

The claims analysis by Varadharajan et al. compared mean annual per patient outpatient costs of 2 cohorts of patients receiving tolterodine ER with matched cohorts of patients receiving oxybutynin ER or oxybutynin IR [58]. It reported that patients on tolterodine ER had significantly lower outpatient management costs (OAB related, $33; all other, $782) than patients on oxybutynin ER (OAB related, $40; all other, $829) [58]. There was no significant difference in OAB-related outpatient management costs between patients treated with tolterodine ER ($34) and oxybutynin IR ($32); however, all other outpatient management costs were lower in the tolterodine ER–treated group ($816) than the oxybutynin-treated group ($923) [58]. OAB-related and all other outpatient ancillary costs were lower for tolterodine ER (OAB related, $72; all other, $2197) than oxybutynin ER (OAB related, $109; all other, $2372) and lower in a second tolterodine ER cohort (OAB related, $82; all other, $2558) than for oxybutynin IR (OAB related, $74; all other, $3076) [58].

Two articles compared outpatient visit costs between patients with OAB receiving anticholinergic medications and a β₃-adrenergic receptor agonist (mirabegron). A 2021 claims analyses by Walker et al. included patients with OAB who were aged ≥65 years, frail (claims-based frailty index [66] score ≥0.25) and taking either anticholinergic medications or mirabegron [59]. It found that patients taking anticholinergic medications had slightly lower monthly outpatient visit costs than patients taking the β₃-adrenergic receptor agonist ($498 vs $549, respectively) [59]. In contrast, the 2016 budget impact model by Perk et al. compared patients with OAB taking anticholinergic medications to patients taking mirabegron and predicted that patients taking anticholinergics would have higher outpatient costs than patients taking mirabegron owing to increased anticholinergic burden–related outpatient visits; the cost of anticholinergic burden related to outpatient visits was estimated at $594.50 (vs $138.90 for mirabegron) for Medicare Advantage and $551.40 (vs $5.58 for mirabegron) for a commercial insurance plan [37].

Three articles reported data or model results on physician visit costs of patients taking anticholinergic medications for OAB. The 2009 claims analysis by Pelletier et al. found that annual physician visit costs were lower among patients with OAB who received an anticholinergic medication (OAB related, $42; all other, $803) than among those who were not pharmacologically managed (OAB related, $70; all other, $892) [52]. Similarly, the 2016 economic impact model by Qin et al. predicted that older adult patients with OAB treated with fesoterodine would have lower annual physician visit costs ($36,239,668 for a cohort of 7096 patients) than those with no pharmacologic management ($39,030,822) [38]. The 2016 budget impact model by Perk et al. assumed that differences in physician visit costs between OAB medications would be most influenced by persistence, with lower persistence (and therefore increased medication switching) driving increased physician visits [37]. The lowest annual physician visit costs per patient were predicted in patients treated with mirabegron (commercial, $248.59; Medicare Advantage, $162.48). Among anticholinergic medications fesoterodine had the lowest physician visit costs (commercial, $456.77; Medicare Advantage, $298.54) and trospium had the highest (commercial, $536.10; Medicare Advantage, $350.39) [37].

Five articles reported data or model results on the emergency department costs of patients taking anticholinergic medications for OAB. Three articles compared patients with OAB taking anticholinergic medications to patients without pharmacologically managed OAB [37,52,60], whereas other articles assessed medication adherence [46] or compared anticholinergic medications [58].

The 2016 claims analysis by Yehoshua et al. reported that patients with OAB wet who were treated with anticholinergic medications had higher average annual emergency department visit costs ($330) than those without OAB ($193) [60]. Similarly, Pelletier et al. found slightly lower OAB-related emergency department costs among patients with OAB who were on an anticholinergic medication ($1) versus those who were not pharmacologically managed ($9; p < 0.001) [52]. A 2016 budget impact model by Perk et al. predicted that patients with OAB taking anticholinergic medications would have higher anticholinergic medication–related emergency department costs than patients not receiving pharmacologic treatment from both the commercial and Medicare Advantage perspectives (commercial, $166.42 vs $1.17, respectively; Medicare Advantage, $216.77 vs $48.98) [37].

The 2014 claims analysis by Ivanova et al. examined the relationship between persistence with OAB medication and emergency department costs in patients with OAB. All-cause emergency department costs were highest among patients who discontinued an anticholinergic medication ($231), followed by those who switched anticholinergic medications ($229) or who persisted with the original anticholinergic medication ($185) [46].

The 2005 claims analysis by Varadharajan et al. compared mean annual per-patient emergency department costs of 2 cohorts of patients receiving tolterodine ER with matched cohorts of patients receiving oxybutynin ER or oxybutynin IR [58]. In each group, the average cost of emergency department visits was $1 for OAB-related visits; average cost of emergency department visits related to other causes ranged from $98–$137 [58].

Two articles reported data or model results on the costs of OAB-related conditions in patients taking anticholinergic medications. A 2016 economic analysis by Qin et al. predicted that a cohort of 7096 patients who were treated with fesoterodine would have lower 1-year costs than nonpharmacologically managed patients for falls/fractures (fesoterodine, $62,308,176 vs no treatment, $66,983,236), UTIs ($8,759,786 vs $10,763,598) and depression ($31,982,765 vs $36,551,387) [38]. A 2006 model by Ko et al. calculated the average cost of falls/fractures over 3 months for patients taking an anticholinergic medication and found that costs ranged from $3373 with solifenacin to $3769 with oxybutynin IR [32].