Moving preinduction cervical ripening to a lower acuity inpatient setting using the synthetic hygroscopic cervical dilator: a cost-consequence analysis for the United States

Figures & data

Figure 1. Illustration of the cost-consequence model. (A) The decision tree for assigning a CRA. In the standard-of-care arm a prostaglandin is assigned and in the comparison arm the SHCD is assigned (grey box). A single patient receives only one type of CRA. Patients are modeled separately depending on their parity. (B) The process from admission to delivery is divided into a ripening, labor, and delivery phase. The ripening room (grey box) is a lower acuity room in comparison to an L&D room without facilities for fetal monitoring or for labor or delivery, and is only used in the model for patients undergoing cervical ripening with the SHCD. A cesarean section required prior to attempted labor was not modeled because it is expected to be rare in a patient population with low to moderate risk pregnancies and it would not change model outcomes. All other events (white boxes) occur in a standard L&D room. Key cost and time parameters are listed in the right-hand box. Abbreviations. CRA, cervical ripening agent; IV, intravenous; L&D, labor and delivery; PGE1, misoprostol; PGE2, dinoprostone; prep., patient preparation before CRA administration; SHCD, synthetic hygroscopic cervical dilator.

Table 1. Base-case cost parameters.

Model input	Input value [SD]	Sources
Purchase of CRA
SHCD	$400.00 [±40.00]	Medicem list price; average of 5 rods^13
PGE2 insert	$456.99 [±45.70]	^23
PGE2 gel	$569.37 [±56.94]	^23
Oral PGE1	$1.00 [±0.10]	^23
Vaginal PGE1	$1.00 [±0.10]	^23
First administration cost
SHCD	$361.73 [±36.17]	^24
PGE2 insert	$361.73 [±36.17]	^24
PGE2 gel	$361.73 [±36.17]	^24
Oral PGE1	$147.64 [±14.76]	50% of vaginal PGE1^25
Vaginal PGE1	$295.28 [±29.53]	^25
Subsequent administration cost
SHCD	$296.62 [±29.66]	^25
PGE2 insert	$296.62 [±29.66]	^25
PGE2 gel	$296.62 [±29.66]	^25
Oral PGE1	$121.01 [±12.10]	50% of vaginal PGE1^25
Vaginal PGE1	$242.01 [±24.20]	^25
Oxytocin and per-patient materials cost	$31.34 [±3.13]	^23^,^26; Henry Schein list price quote
IV initiation cost	$73.90 [±7.39]	^26
Cost of L&D room per hour	$133.46 [±13.35]	^24
Cost of the ripening room (proportion of L&D room)	30%	Assumption

Abbreviations. CRA, cervical ripening agent; IV, intravenous; L&D, labor and delivery; PGE1, misoprostol; PGE2, dinosprostone; SD, standard deviation; SHCD, synthetic hygroscopic cervical dilator.

All costs are given or inflated to 2020 US dollars (USD).

Table 2. Selected base-case parameters for population and IOL protocols.

Model input	Input value [SD]	Sources
Nulliparous, %	38.5 [±3.8]	^27
First patient preparation, min	45.0 [±4.5]	^25
Nurse	35.0 [±3.5]	^25
Resident	10.0 [±1,0]	^25
Physician	5.0 [±0.5]	^25
Subsequent patient preparation, min	25.0 [±2.5]	^25
Nurse	15.0 [±1.5]	^25
Resident	3.0 [±0.3]	^25
Physician	0.0 [±0.1]	^25
Administration of CRA, h	20.0 [±2.0]	^25
Nurse	20.0 [±2.0]	^25
Resident	2.0 [±0.2]	^25
Physician	0.0 [±0.1]	^25
Number of administrations, mean (base case)
SHCD	1.13 [±0.13]	^13
PGE2 insert	1.01 [±0.10]	^28
PGE2 gel	1.75 [±0.75]	^29
Oral PGE1	3.00 [±0.30]	^30
Vaginal PGE1	2.00 [±0.20]	^30
Number of administrations, mean (scenario analysis 4)
Oral PGE1	5.00 [±0.5]	^30(50 mcg counted as two doses of 25 mcg)
Vaginal PGE1	3.00 [±0.3]	^30(50 mcg counted as two doses of 25 mcg)
Monitoring protocol
SHCD	30 min	Standard non-stress test plus 10 min on average for irregular extended monitoring
PGE2 insert	constant	^5
PGE2 gel	constant	Assumption
Oral PGE1	2 h	^5
Vaginal PGE1	4 h	^5
Nurse-to-patient ratio, nurses:patients
Fetal monitoring	1:2	^5^,^25
Oxytocin augmentation	1:1	^5^,^22
Active labor to delivery	1:1	^22
Time spent in the ripening room with SHCD, h
Nulliparous	4.59 [±0.59]	^11^,^13
Multiparous	3.40 [±0.34]	^11^,^13^,^31

Abbreviations. CRA, cervical ripening agent; h, hours; min, minutes; PGE1, misoprostol; PGE2, dinosprostone; SD, standard deviation; SHCD, synthetic hygroscopic cervical dilator.

See the Supplementary material for more details on study selection and calculations performed.

Table 3. Overview of calculated CRA-related costs and consequences.

Model input	SHCD	PGE2 insert	PGE2 gel	Oral PGE1	Vaginal PGE1	Ref
CRA-related costs, mean [95% CrI], base case	$3,210 [$2,303–$3,860]	$4,028 [$3,003–$5,812]	$4,104 [$3,150–$4,856]	$3,481 [$2,618–$5,199]	$2,750 [$2,108–$3,992]	NA
Nulliparous	$3,647 [$2,708–$4,597]	$4,974 [$3,813–$6,295]	$4,574 [$3,568–$5,612]	$4,457 [$3,221–$6,931]	$3,448 [$2,541–$5,233]	NA
Multiparous	$2,936 [$2,015–$3,460]	$3,435 [$2,476–$5,575]	$3,810 [$2,822–$4,466]	$2,869 [$2,222–$4,154]	$2,314 [$1,823–$3,253]	NA
CRA-related nurse time (h), mean [95% CrI], base case	10.22 [2.19–17.21]	17.27 [7.56–30.53]	13.76 [7.26–18.69]	14.26 [3.28–28.31]	11.19 [4.03–20.24]	NA
Nulliparous	11.98 [2.41–21.36]	22.33 [11.69–32.81]	16.34 [8.74–23.68]	17.27 [0.61–39.73]	13.81 [0.77–29.34]	NA
Multiparous	9.13 [1.20–15.47]	14.11 [3.89–30.14]	12.15 [5.48–16.59]	12.37 [2.92–23.03]	9.02 [3.35–16.28]	NA
^aPrimary cesarean section rate, %, mean [BP 95% CI]
Nulliparous	25.5 [±8.5]	38.2 [±9.5]	26.2 [±8.6]	28.1 [±8.8]	26.6 [±8.7]	^13^,^14^,^27
Multiparous	8.1 [±5.3]	9.6 [±5.8]	16.4 [±7.3]	8.9 [±5.6]	8.4 [±5.4]	^13^,^14^,^27
^aOxytocin augmentation, %, mean [BP 95% CI]	80.4 [±7.8]	50.6 [±9.8]	74.4 [±8.6]	63.0 [±9.5]	50.0 [±9.8]	^14
^aVaginal delivery not within 24 h, %, mean [BP 95% CI]	54.0 [±9.8]	53.5 [±9.8]	53.5 [±9.8]	42.2 [±9.7]	49.5 [±9.8]	^14
^aUterine hyperstimulation with FHR changes,%, mean [BP 95% CI]	1.5 [±2.4]	4.3 [±4.0]	4.1 [±3.9]	1.9 [±2.7]	3.8 [±3.7]	^14
^aTime to delivery (h), median [IQR]
Nulliparous	23.5 [17.7–29.6]	30.7 [23.0–38.7]	21.8 [16.4–27.5]	30.0 [21.8–46.6]	21.4 [15.6–33.3]	^13^,^28^,^30^,^31
Multiparous	17.4 [11.3–20.4]	19.2 [12.5–33.3]	16.1 [10.5–18.9]	18.1 [13.9–26.2]	12.9 [9.9–18.7]	^13^,^28^,^30^,^31

All clinical outcomes were normalized using a common comparator CRA. Full calculations are given in the Supplementary Material. Oxytocin augmentation and times to delivery were a part of the CRA-related cost calculation; other outcomes are reported as consequences only. Costs are given in 2020 USD.

Abbreviations. CRA, cervical ripening agent; FHR, fetal heart rate; h, hours; IQR, interquartile range; NA, not applicable, this is an output of the cost-consequence model; PGE1, misoprostol; PGE2, dinosprostone; Ref, reference for source of original data; SHCD, ripening room using the synthetic hygroscopic cervical dilator; 95% CrI, 95% credible interval computed by parametric sensitivity analysis; BP 95% CI, the binomial proportion 95% confidence interval using the binomial distribution using the patient population size of the original study or 100, note that it is symmetric around the mean.

^aIt must be considered that the clinical consequences were calculated from several sources of clinical trials and represent a theoretical outcome of the model – they are to be regarded as estimates only and not evidence based directly on clinical data or meta-analyses thereof.

Figure 2. Estimated costs associated with the administration of each type of CRA based on an average US clinical practice for IOL. (A) Total CRA-related cost per CRA in the base case. (B) Cost difference when comparing the SHCD to each of the prostaglandins stratified by parity. The total estimated cost for the ripening room using SHCDs was $2,936 for multiparous and $3,647 for nulliparous patients using the base case for all other parameters. Abbreviations. CRA, cervical ripening agent; PGE1, misoprostol; PGE2, dinoprostone; SHCD, ripening room using the synthetic hygroscopic cervical dilator. Costs are given in 2020 USD.

Figure 3. Estimated nurse time associated with the administration of each type of CRA based on an average US clinical practice for IOL from admission to delivery. (A) Total CRA-related nurse time for each CRA in the base case. (B) Difference in nurse time when comparing the SHCD to each of the prostaglandins stratified by parity. The total nurse time for the SHCD was 9.13 h for multiparous and 11.98 h for nulliparous patients. Abbreviations. h, hours; PGE1, misoprostol; PGE2, dinoprostone; SHCD, ripening room using the synthetic hygroscopic cervical dilator.

Figure 4. Illustrating the impact of changing the cost of the ripening room proportionally to the L&D room cost when using the SHCD. The per-hour cost for the ripening room was tested from 10% to 100% of the L&D room (shown as a black line). The grey rectangle between 20% and 40% represents a reasonable cost range for the ripening room in comparison to the L&D room. For comparison, the prostaglandin costs are given as grey dots along the 100% line. If the patient remains in the L&D room and does not transfer to a ripening room, the maximum possible costs were $3,570 (at the 100% line in light grey), which $89 higher than the cost for oral PGE1. Costs are given in 2020 USD. Abbreviations. CRA, cervical ripening agent; L&D, labor and delivery; PGE1, misoprostol; PGE2, dinosprostone; SHCD, synthetic hygroscopic cervical dilator.

Figure 5. In scenario 2, we compared using a mix of prostaglandins in the standard of care (SOC) with switching to protocol including a ripening room and SHCDs. Comparisons are made in terms of (A) estimated CRA-related costs, (B) CRA-related nurse time, (C) cesarean deliveries, and (D) uterine deliveries with fetal-heart-rate (FHR) changes. The proportions used for the prostaglandins were taken from studies based on US patient data^5,32,33. Costs are given in 2020 USD. Abbreviations. CRA, cervical ripening agent; PGE1, misoprostol; PGE2, dinosprostone; SHCD, synthetic hygroscopic cervical dilator.

Table 4. Sensitivity analyses for the base case and scenario 2 for costs and nurse time.

	% of tests the SHCD is better	Median	95% CrI
CRA-related cost savings for the ripening room using SHCDs compared with each prostaglandin
PGE2 insert	88.9%	−$1,205	−3,256 to $636
PGE2 gel	92.3%	−$948	−$2,269 to $398
Oral PGE1	77.6%	−$777	−$2,587 to $1,037
Vaginal PGE1	46.9%	$71	−$1467 to $1,539
CRA-related nurse-time savings for the ripening room using SHCDs vs each prostaglandin (h)
PGE2 insert	85.7%	−9.18 h	−24.55 to 5.73 h
PGE2 gel	72.9%	−3.51 h	−13.24 to 6.36 h
Oral PGE1	79.0%	−6.24 h	−20.65 to 8.59 h
Vaginal PGE1	65.8%	−2.69 h	−14.69 to 9.59 h
The ripening room using SHCDs compared with a mixed-case use of prostaglandins (scenario 2)
CRA-related costs	85.6%	−$731	−$2,051 to $544
CRA-related nurse time (h)	87.7%	−6.48 h	−16.72 to 4.66 h
Rank of the ripening room using SHCDs with 1 = best to 5 = worst of all CRAs in scenario 2		Mean
CRA-related cost		1.94
CRA-related nurse time		1.97

Abbreviations. CRA, cervical ripening agent; scenario 2, Comparing a mixed-case population where each patient receives only one but possibly different type of prostaglandins with a population receiving only the SHCD with a ripening room (see Methods); CrI, credible interval; CRA, cervical ripening agent; PGE1, misoprostol; PGE2, dinosprostone; SHCD, synthetic hygroscopic cervical dilator.

Figure 6. Ranking for each CRA separately when comparing (A) CRA-related costs and (B) nurse time in the sensitivity analysis. 2,000 parameter settings were tested and the output for each parameter set was the rank for each CRA from 1 (best) to 5 (worst). Abbreviations. CRA, cervical ripening agent; L&D, labor and delivery; PGE1, misoprostol; PGE2, dinosprostone; SHCD, synthetic hygroscopic cervical dilator.

Saad AF, Villarreal J, Eid J, et al. A randomized controlled trial of Dilapan-S vs foley balloon for preinduction cervical ripening (DILAFOL trial). Am J Obstet Gynecol. 2019;220(3):275.e1-275–e9.

 Web of Science ®Google Scholar

Micromedex IBM. (R) [database online]. RED book online. Truven health analytics/IBM Watson gealth. 2021. https://www.micromedexsolutions.com

 Google Scholar

Son SL, Benson AE, Hart Hayes E, et al. Outpatient cervical ripening: a cost-minimization and threshold analysis. Am J Perinatol. 2020;37(3):245–251.

 PubMed Web of Science ®Google Scholar

ACOG Education & Events. Inpatient versus outpatient induction of labor. The American College of Obstetricians and Gynecologists (ACOG). 2021. https://www.acog.org/education-and-events/creog/curriculum-resources/cases-in-high-value-care/inpatient-versus-outpatient-induction-of-labor

 Google Scholar

Palmer PP, Lemus B, DiDonato K, et al. Cost of delivering intraveneous opioid analgesia in emergency departments in the United States. Value Heal. 2016;19(3):A246–A247.

 Web of Science ®Google Scholar

Hehir MP, Ananth CV, Siddiq Z, et al. Cesarean delivery in the United States 2005 through 2014: a population-based analysis using the robson ten group classification system. Am J Obstet Gynecol. 2018;219(1):105.e1–105.e11.

 PubMed Web of Science ®Google Scholar

Miller H, Goetzl L, Wing DA, et al. Optimising daytime deliveries when inducing labour using prostaglandin vaginal inserts. J Matern Fetal Neonatal Med. 2016;29(4):517–522.

 PubMed Web of Science ®Google Scholar

Ogbonna BN, Cabais F, Shabban M. Dinoprostone intracervical gel for cervical ripening. Int J Gynaecol Obstet. 2004;87(1):40–41.

 PubMed Web of Science ®Google Scholar

Haas DM, Daggy J, Flannery KM, et al. A comparison of vaginal versus buccal misoprostol for cervical ripening in women for labor induction at term (the IMPROVE trial): a triple-masked randomized controlled trial. Am J Obstet Gynecol. 2019;221(3):259.e1-259–259.e16.

 Web of Science ®Google Scholar

Simpson KR. Cervical ripening and labor induction and augmentation, 5th edition. J Obstet Gynecol Neonatal Nurs. 2020;49(5):S1–S41.

 PubMed Web of Science ®Google Scholar

Simpson KR, Lyndon A, Spetz J, et al. Adherence to the AWHONN staffing guidelines as perceived by labor nurses. Nurs Womens Health. 2019;23(3):217–223.

 PubMedGoogle Scholar

Ausbeck EB, Jauk VC, Xue Y, et al. Outpatient foley catheter for induction of labor in nulliparous women: a randomized controlled trial. Obstet Gynecol. 2020;136(3):597–606.

 PubMed Web of Science ®Google Scholar

Levine LD, Downes KL, Elovitz MA, et al. Mechanical and pharmacologic methods of labor induction: a randomized controlled trial HHS public access author manuscript conclusion-after censoring for cesarean and adjusting for parity, misoprostol-cervical foley resulted in twice the chance of deliver. Obs. Gynecol. 2016;128(6):1357–1364.

 PubMed Web of Science ®Google Scholar

de Vaan MD, Ten Eikelder ML, Jozwiak M, et al. Mechanical methods for induction of labour. Cochrane Database Syst Rev. 2019;10:CD001233.

 PubMedGoogle Scholar

Mendez-Figueroa H, Bicocca MJ, Gupta M, et al. Labor induction with prostaglandin E1 versus E2: a comparison of outcomes. J Perinatol. 2021;41(4):726–735.

 PubMed Web of Science ®Google Scholar

Dorr ML, Pierson RC, Daggy J, et al. Buccal versus vaginal misoprostol for term induction of labor: a retrospective cohort study. Am J Perinatol. 2019;36(7):765–772.

 PubMed Web of Science ®Google Scholar