Stated preferences for human papillomavirus vaccination for adolescents in selected communities in Ibadan, Southwest Nigeria: A discrete choice experiment

Figures & data

Table 1. Identified attributes of the HPV vaccine and their levels.

Attributes of HPV vaccine	Level 1	Level 2	Level 3
Other added benefits	Prevention of cancer of the head and neck	Prevention of genital warts	Prevention of anal cancer
Frequency of severe side effects	1/1000	1/10,000	1/100,000
Out of pocket payment (N)	N14,000*	N21,000#	Government pays
Location of the vaccination services	School based services	Health facility- based services	Community based services
Number of doses required	2 doses	3 doses
Effectiveness in the prevention of cancer of the cervix	70%	90%

*Equal to $38.89 for the two-dose course.

#Equal to $56. 91 for the three-dose course.

Table 2. Sociodemographic characteristics of participants in the discrete choice experiment to determine societal preference of HPV vaccine*.

Characteristics	Frequency	Percentage
Gender
Male	248	35.4
Female	452	64.5
Age-group (years)
10-19	144	20.7
20-44	393	56.6
≥45	157	22.6
Religion
Christianity	256	36.6
Islam	431	61.6
Traditionalist	9	1.2
Socioeconomic class
High	365	52.1
Middle	192	27.5
Low	142	20.3
Ethnicity
Yoruba	676	96.6
Igbo	18	2.6
Hausa	4	0.6
Others	2	0.2

*There were some non-responses.

Table 3. Societal preference for HPV vaccination for adolescents in selected communities in Ibadan, Nigeria.

	Conditional logit		Mixed logit
Attribute	Coeff.	[95% CI]	Coeff.	95% CI
Opt-out constant	−1.31	[−1.96, −0.67]	−2.88	[−3.81, −1.96]
Out-of-pocket payment (N)	−0.14	[−0.15, −0.13]	−0.21	[−0.23, −0.19]
Frequency of severe side effects	−155.67	[−300.60, −10.73]	−270.59	[−479.15, −62.02]
Effectiveness	0.85	[0.12, 1.58]	0.66	[−0.40, 1.73]
Location of service
Health facility	reference		reference
School	0.11	[−0.05, 0.3]	0.03	[−0.21, 0.27]
Community	−0.17	[−0.35, 0.002]	−0.34	[−0.59, −0.09]
Number of required doses
2 doses	reference		reference
3 doses	0.05	[−0.07, 0.17]	0.04	[−0.15, 0.22]
Added benefits prevention
Head and neck cancers	reference		reference
Anal cancer	0.05	[−0.14, 0.25]	0.03	[−0.27, 0.34]
Genital warts	0.09	[−0.06, 0.25]	0.15	[−0.08, 0.38]

Attributes in bold were included as continuous variables in the regression model, whereas the non-bold variables were included as binary dummy variables (with the reference categories included for ease of interpretation).

Table 4. Interaction between the respondents’ characteristics and the preference for attributes of the HPV vaccine.

Attribute	Age 20 – 44 (vs Age 10-19)	Age 45+ (vs Age 10-19)	Christian (vs Non-Christian)	Mid SES (vs Low SES)	High SES (vs Low SES)
Model 1: Cost interactions	−0.05 (p < .01)	−0.07 (p < .01)	−0.02 (p < .01)	0.03 (p < .01)	0.03 (p < .01)
Model 2: Effectiveness interactions	0.28 (p = .08)	0.14 (p = .43)	−0.10 (p = .39)	0.63 (p < .01)	0.71 (p < .01)
Model 3: Side-effect interactions	339.90 (p = .06)	34.06 (p = .87)	−27.78 (p = .83)	294.22 (p = .16)	240.11 (p = .18)
Model 4: Location of service interactions
School-facility (vs health-facility)	−0.74 (p < .01)	−0.78 (p < .01)	−0.06 (p = .65)	0.49 (p = .02)	0.24 (p = .18)
Community-facility (vs health-facility)	0.52 (p < .01)	0.52 (p < .01)	−0.08 (p = .55)	0.69 (p < .01)	0.43 (p = .02)
Model 5: Dose (3 vs 2) interactions	−0.04 (p = .77)	−0.15 (p = .37)	−0.09 (p = .41)	0.46 (p < .01)	0.22 (p = .14)
Model 6: Added benefit interactions
Anal cancer (vs head & neck cancer)	−0.39 (p = .07)	−0.73 (p < .01)	−0.06 (p = .69)	0.99 (p < .01)	0.66 (p < .01)
Genital warts (vs head & neck cancer)	0.28 (p = .12)	0.08 (p = .70)	−0.24 (p = .06)	0.38 (p = .07)	0.53 (p < .01)

This table shows results from six conditional logit models with each row representing the results from separate conditional logit model (as in Table 3) with interaction variables – i.e., the first row is a conditional logit model where the cost attribute was interacted with the individual characteristics seen in each column.