RESEARCH ARTICLE
Correlates to Human Papillomavirus Vaccination Status and Willingness to Vaccinate in Low-Income Philadelphia High School Students Sarah B. Bass, PhD, MPHa Amy Leader, DrPHb Michelle Shwarz, PhD, MSEdc Judith Greener, MAd Freda Patterson, PhD, MSe
ABSTRACT BACKGROUND: Little is known about the correlates of human papillomavirus (HPV) vaccination or willingness to be vaccinated in urban, minority adolescents. METHODS: Using responses to the 2013 Youth Risk Behavior Survey in Philadelphia, a random sample of high schools provided weighted data representing 20,941 9th to 12th graders. Stratified by either having had or willingness to have the vaccine, bivariate analysis with sexual behavior, preventive health behaviors, mental health, substance use, and demographic characteristics were examined and then multivariable regression models were developed to estimate significant correlates. RESULTS: Respondents were 52.3% female, 84.4% non-White, and 65.9% ≥16 years; 43% reported having had the HPV vaccine, and of those not vaccinated, 66% reported willingness to be vaccinated. Logistic regression models indicate that females (odds ratio [OR] = 3.12, p < .01) and those reporting human immunodeficiency virus (HIV) testing (OR = 2.10, p < .01) were more likely to be vaccinated. Those reporting condom use during last intercourse (OR = 0.40; p = .05) and current marijuana use (OR = 0.37; p = .03) were less likely to indicate willingness to be vaccinated. CONCLUSIONS: Important areas for intervention include addressing misconceptions or feelings of ‘‘immunity,’’ especially for those using condoms. Understanding the correlation between HIV testing and HPV vaccination is also an important intervention opportunity for schools hoping to increase adolescent vaccination rates. Keywords: human papillomavirus; HPV; HPV vaccination: Youth Risk Behavior Survey; adolescent health; sexual health. Citation: Bass SB, Leader A, Shwarz M, Greener J, Patterson F. Correlates to HPV vaccination status and willingness to vaccinate in low-income Philadelphia high school students. J Sch Health. 2015; 85: 527-535. Received on June 30, 2014 Accepted on January 9, 2015
H
uman papillomavirus (HPV) is the most common sexually transmitted infection (STI) in both sexually active young adults and adolescents.1 It causes approximately 70% of cervical cancer cases2 in women and is regarded as the primary cause of anal, penile, and oral cancers in men.3 Experimental and epidemiological data suggests that HPV is the second most common risk factor for cancer development in humans, exceeded only by tobacco use.4 While death rates for the majority of cancers continue to
decline for men and women in the United States, incidence rates for HPV-related cancers, particularly oropharynx and anal, have increased substantially.5 This is especially true in minority men and women, who have either higher rates of HPV related cancers or higher mortality.5,6 Besides its oncogenic properties, HPV is also associated with 90% of the more than 500,000 cases of genital warts,7,8 making it a key target for public health intervention. In 2006 the Food and
a
Associate Professor, ([email protected]), Department of Public Health, Temple University, 1301 Cecil B. Moore Avenue, 9th Floor, Philadelphia, PA 19122. Assistant Professor, ([email protected]), Department of Medical Oncology, Division of Population Science, Thomas Jefferson University, 834 Chestnut Street, Suite 314, Philadelphia, PA 19107. c Research Assistant, ([email protected]), Department of Public Health, Temple University, 1301 Cecil B. Moore Avenue, 9th floor, Philadelphia, PA 19122. d Research Assistant, ([email protected]), Department of Public Health, Temple University, 1301 Cecil B. Moore Avenue, 9th floor, Philadelphia, PA 19122. e Assistant Professor, ([email protected]), Department of Public Health, Temple University, 1301 Cecil B. Moore Avenue, 9th floor, Philadelphia, PA 19122. b
Address correspondence to: Sarah B. Bass, Associate Professor, ([email protected]), Department of Public Health, Temple University, 1301 Cecil B. Moore Avenue, 9th Floor, Philadelphia, PA 19122. Funding was provided by Centers for Disease Control and Prevention, # 1U87PS004152-01.
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Drug Administration licensed quadrivalent human papillomavirus vaccine for use in girls and 2009 in boys and the Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices now recommends vaccination for HPV in both adolescent boys and girls at ages 11 or 12 as part of the regular vaccination schedule.9,10 As a result, research indicates that between 2006 and 2010, the prevalence of HPV-targeted infections decreased by more than half in adolescent girls,11 with HPV vaccination rates doubling from 25.1% in 2007 to 53.0% in 2011. However, 2012 vaccination initiation rates failed to increase significantly for girls.12 Similarly, rates of HPV vaccination among age-eligible boys, despite the new guidelines, are also suboptimal, ranging from just 2% to 20% in most survey samples.12,13 Geographic disparities in HPV vaccination rates have also been documented, indicating that poorer counties and families with lower income and levels of education have higher female vaccination rates, possibly because poorer areas tend to have more subsidized resources for health care services.14 This is reflected in the Philadelphia area. The National Immunization Survey-Teen (NIS-Teen) showed that in 2012, 13- to 17-year-old male and female adolescents in Philadelphia county had higher rates of vaccination than teens across the state of Pennsylvania and nationally.15 However, the NIS-Teen did not explore predictors of vaccination uptake or intention to vaccinate. Understanding the correlates of HPV vaccine uptake in both boys and girls, especially urban, at-risk adolescents, can help inform opportunities to increase vaccination rates. Previous research has shown that accessing health care, especially for sexual and mental health issues, is a predictor of HPV vaccine uptake.16 However, little is known about HPV vaccine uptake and willingness to receive the vaccine in high-risk, low-income urban adolescents. Most recent literature has focused on vaccination barriers among parents, or compared parent and child perceptions of vaccination.17-19 The majority of these have been with parents of female children16,20-22 and few have been done in urban, largely minority low-income groups.19 The few that have examined urban and/or minority groups have had small sample sizes, sampled only from 1 location and only focused on either girls and their parents or boys and their parents.21,23-26 In addition, while there have been a few larger sample studies,27 most have not examined health behaviors other than sexual behaviors as predictive correlates of being vaccinated or willingness to be vaccinated, have included only girls and have not focused on a large urban area. This study fills this gap by examining self-reported behaviors of Philadelphia high school students as part of the Youth Risk Behavior Survey (YRBS). Following is a report of 528 •
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correlates in both male and female students for having received the HPV vaccine or willingness to receive the vaccine in a weighted sample. No other YRBS has asked specifically about HPV vaccination, so results substantially add to the literature and can inform the development of proposed interventions in urban areas.
METHODS Participants The School District of Philadelphia oversees the YRBS survey in Philadelphia, with Temple University conducting the survey and analyzing data as the subcontractor. A 2-stage, cluster sample design is used to produce a representative sample of students. In the first stage, schools are selected with probability proportional to school enrollment size. In the second stage, intact classes of a required subject or intact classes during a required period are then selected randomly. Schools are contacted and instructed on what classes have been chosen to participate. All students in sampled classes are eligible to participate.28 If the survey’s response rate is at least 70%, samples can be weighted for data analysis. For this analysis, all high schools randomly selected in the Philadelphia School District (N = 32) participated. The student response rate was 71% (1280/1804). The study population included 1080 students, weighted to a population estimate of 20,941 to account for oversampling of minority groups. Instrument The YRBS is a biennial, self-administered survey of US high school students, administered at the national level by CDC and by states, territories, tribal areas, or large urban school districts; it is conducted during February to May of each oddnumbered year.28 Conducted since 1991, the surveys include representative samples of students in grades 9-12 and monitor 6 categories of priority health-risk behaviors.28 The standard 2013 YRBS questionnaire includes 5 demographic questions, 23 questions related to unintentional injuries and violence, 10 on tobacco use, 18 on alcohol and other drug use, 7 on sexual behavior, 16 on body weight and dietary behaviors, 5 on physical activity, and 2 on other health-related topics, such as asthma and sleep.28 (The 2013 questionnaire is available at http://www.cdc.gov/yrbss) Sites can also modify the standard questionnaire within certain parameters. Two thirds of the original questions must be retained and no more than 8 additional questions with mutually exclusive answers can be added. In addition, no more than a total of 99 questions can be included, to ensure that the questions can be completed in a single class period by all students.28 While sites can choose from
© 2015, American School Health Association
a list of optional questions, we received permission to include 2 new questions related to HPV vaccination, which has not been done in any other YRBS survey. Specific questions were: ‘‘Have you ever had the HPV vaccine?’’ (0 = no, 1 = yes) and ‘‘If your doctor recommended the HPV vaccine, would you get it?’’ (0 = no, 1 = yes). These outcome measures were then used in analysis with independent variables, including demographic characteristics, sexual health behaviors, mental health outcomes, and other health behaviors. For the question related to willingness to vaccinate, students who indicated that they had already been vaccinated (ie, any student who answered ‘‘yes’’ to ‘‘Have you ever had the HPV vaccine?’’) were excluded. Specific study variables are listed in Tables 1 and 2. Procedure Parental permission is obtained before administering the YRBS, according to each school district’s requirements. Trained data collectors travel to each school and administer the surveys using a standardized script and record the grade level of the class and number of students enrolled. All answers are anonymous and voluntary and students complete the self-administered questionnaire during 1 class period, recording their responses on a computerscannable answer sheet.28 All policies and procedures are approved through the Temple University Institutional Review Board. Data Analysis Statistical analyses were conducted on weighted data using the complex samples module of SPSS, version 20. Descriptive statistics and F tests were used to examine the demographic and health behavior characteristics of the sample for both outcome variables. Variables associated with these outcomes at the p ≤ .20 level were entered into multivariable regression models to estimate significant correlates for each independent association. Sampling errors were calculated through Taylor series linearization. Sampling weights were used to adjust for nonresponse and oversampling. Significance values of .05 were used to assess effect.
RESULTS Participant Characteristics The weighted sample was 52.3% female. Over half the sample was African American (56.2%), while 15.6% was Caucasian, 6.7% Asian, and the remaining 21.5% from another racial group. The sample was evenly distributed across grade levels: 28.3% was in 9th grade, 24.8% in 10th grade, 25.1% in 11th grade, and 21.5% in 12th grade. Journal of School Health
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Correlates of Having Received the HPV Vaccination Overall, 42.9% of the sample reported having received the HPV vaccine. Age, sex, and race were all significantly associated with being vaccinated. Specifically, a greater proportion of girls as compared with boys (53.4% vs 31.4%; Fadj = 60.71, p ≤ .001) and students ≥16 years as compared with ≤15 years (46.5% vs 36.0%; Fadj = 7.44, p ≤ .01) were vaccinated. A significantly smaller proportion of Asian (20.5%) as compared with White (47.5%), Black (43.6%), and students from ‘‘other’’ (44.8%) racial groups had been vaccinated (Fadj = 6.12, p < .01). Sexual health variables that were correlated with having received the HPV vaccine included having been tested for human immunodeficiency virus (HIV), having had sex with at least 4 people and being currently sexually active. Higher proportions of students who had been tested for HIV (55.3% vs 33.6% who were not tested; Fadj = 41.11, p ≤ .01), reported having sex with ≥4 people in their lifetime (52.5% vs 40.2% who had not; Fadj = 6.08, p = .02), and who reported having sex with ≥1 people in the last 3 months (52.7% vs 36.9% who had not; Fadj = 29.36, p ≤ .01) reported being vaccinated for HPV. Other health behaviors were also found to be correlated with vaccination. A greater proportion of students who had considered suicide in the last year reported having had the vaccine (51.1% vs 43.8% of students who had not; Fadj = 5.15, p ≤ .05). In addition, several current substance use variables were found to correlate with HPV status. A greater proportion of students who reported current alcohol use (52.2% vs 36.3% who did not currently drink; Fadj = 31.06, p ≤ .01), current binge drinking (59.2% vs 39.4% who did not report current binge drinking; Fadj = 25.03, p ≤ .01), and current marijuana use (51.3% vs 41.1% who did not report current marijuana use; Fadj = 13.18, p ≤ .01) were vaccinated. To identify independent correlates of receiving the HPV vaccine, a multivariable logistic regression model was estimated. Variables associated with having received the HPV vaccine at the p < .2 level were included and the Odds ratio, 95% confidence interval, and Bonferroni significance level reported (Table 3). Results showed that girls had a 3-fold greater likelihood of being vaccinated than boys (odds ratio [OR] = 3.12, p < .01), while students who reported being tested for HIV also had a 2-fold greater likelihood of being vaccinated for HPV (OR = 2.10, p < .01). These associations were adjusted for race, use of condom during last intercourse and age. Correlates of Willingness to Receive or Not Receive the HPV Vaccination Among students who reported not having had the HPV vaccine, 66.2% (population estimate of 10,982
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Table 1. Correlates of Having Received the HPV Vaccine Yes Variable
Estimate
SE
No %
N
Demographics Sex Girls 8111 731 53.4 327 Boys 4353 422 31.4 143 Age (years) ≤15 ≤15 3559 640 36 ≥16 ≥16 8905 845 46.5 Race White 2158 474 47.5 74 Black 7109 959 43.6 224 Asian 396 85 20.5 26 Other 2802 317 44.8 146 Grade 9th 2830 738 34.4 77 10th 3153 529 43.8 149 11th 3328 666 45.7 137 12th 3095 656 49.5 105 Other 59 42 72.6 2 Sexual health Had sex for the first time before 13years of age Yes 1132 261 42.4 34 No 10,241 814 42.6 401 Had sex with ≥4 people in their life Yes 2949 410 52.5 102 No 8375 661 40.2 330 Students who had sex with ≥1 people in the last 3months Yes 5253 591 52.7 186 No 6170 621 36.9 250 Among sexually active students, used a condom during last intercourse Yes 2640 440 48.8 94 No 2368 267 57.9 84 Been pregnant or had gotten someone pregnant ≥1 Yes 1242 257 54.2 42 No 11,058 1017 41.9 423 Used alcohol or drugs before last intercourse Yes 1198 258 57.5 37 No 3968 417 51.1 145 Has ever been tested for HIV Yes 6751 639 55.3 237 No 5350 590 33.6 219 Mental health Mental health not good for at least 1day in the last 30days Yes 7218 701 41.7 284 No 5133 506 44.6 183 Ever considered suicide Yes 1955 263 51.1 72 No 10,352 837 41.4 393 Ever attempted suicide Yes 972 167 51.2 36 No 9162 858 43.8 354 Current substance use (≥1 use in last 30days) Tobacco Yes 889 163 44.7 35 No 10,720 862 42.6 407 Alcohol Yes 4335 384 52.2 161 No 6098 548 36.3 240 Binge drinking Yes 2305 290 59.2 88 No 9505 775 39.4 360 Marijuana Yes 3557 456 51.3 127 No 8411 596 40.1 327
Estimate
SE
%
46.6 68.6
125 345
6337 10,240
2384 9200 1539 3454
527 1249 277 407
52.5 56.4 79.5 55.2
78 272 90 170
6.12
5400 4044 3960 3153 22
1399 813 764 853 22
65.6 56.2 54.3 50.5 27.4
148 189 162 110 1
3.12*
1538 13,788
171 1582
57.6 57.4
50 517
0.001
2668 12,450
333 1540
47.5 59.8
86 473
6.08*
4715 10,555
434 1380
47.3 63.1
162 403
29.36**
2767 1720
359 317
51.2 42.1
98 56
1.83
1048 15,309
205 1631
45.8 58.1
35 567
3.51
883 3790
198 408
42.5 48.9
29 131
0.61
5462 10,589
557 1306
44.7 66.4
184 412
41.12**
10,087 6385
1187 673
58.3 55.4
383 225
0.97
1872 14,652
333 1366
48.9 58.6
69 539
5.15*
928 11,779
205 1356
48.8 56.2
35 445
1.29
1102 14,456
253 1511
55.3 57.4
42 535
0.10
3969 10,695
588 1160
47.8 63.7
143 398
31.06**
1591 14,650
305 1469
40.8 60.6
59 538
25.03**
3380 12,539
397 1443
48.7 59.9
117 471
13.18**
HPV, human papillomavirus; HIV, human immunodeficiency virus.
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60.71**
991 871
1364 1039
© 2015, American School Health Association
285 325
Adjusted F
7065 9513
** p ≤ .01; * p ≤ .05.
530 •
N
64 53.5
7.44**
Table 2. Correlates of Willingness to Get the HPV Vaccine Yes Variable
Estimate
SE
No %
Demographics Sex Girls 4587 757 64.9 Boys 6395 628 67.2 Age (years) ≤15 4127 861 65.1 ≥16 6856 853 66.9 Race White 1662 434 69.7 Black 6115 902 66.5 Asian 1038 209 67.5 Other 2167 278 62.7 Grade 9th 3495 886 64.7 10th 2486 507 61.5 11th 2970 615 75.0 12th 2009 604 63.7 Other 22 22 100 Sexual health Had sex for the first time before 13years of age Yes 986 152 64.1 No 8993 1130 65.2 Had sex with ≥4 people in their life Yes 1641 321 61.5 No 8214 1119 66.0 Students who had sex with ≥1 people in the last 3months Yes 2894 379 61.4 No 7058 961 66.9 Among sexually active students, used a condom during last intercourse Yes 1549 272 56.0 No 1184 242 68.8 Been pregnant or had gotten someone pregnant ≥1 Yes 556 180 53.1 No 10, 283 1167 67.2 Used alcohol or drugs before last intercourse Yes 644 198 72.9 No 2208 330 58.3 Has ever been tested for HIV Yes 3150 344 57.7 No 7400 1003 69.9 Mental health Mental Health not good for at least 1day in the last 30days Yes 6293 836 62.4 No 4689 558 73.4 Ever considered suicide Yes 1184 273 63.2 No 9776 969 66.7 Ever attempted suicide Yes 527 148 56.8 No 7919 951 67.2 Current substance use (≥1 use in last 30days) Tobacco Yes 791 193 71.7 No 9528 1070 65.9 Alcohol Yes 2570 439 64.7 No 7045 802 65.9 Binge drinking Yes 980 214 61.6 No 9809 1064 67.0 Marijuana Yes 1926 362 57.0 No 8571 1085 68.4
N
Estimate
SE
%
N
Adjusted F
184 212
2477 3118
322 477
35.1 32.8
101 113
0.28
129 267
2210 3385
589 375
34.9 33.1
72 142
0.15
53 177 62 104
722 3085 501 1287
157 526 124 187
30.3 33.5 32.5 37.3
25 95 28 66
0.44
94 117 118 66 1
1904 1558 989 1144
588 383 197 340
35.3 38.5 25.0 36.3
54 72 44 44
1.55
29 332
552 4794
133 612
35.9 34.8
21 185
0.03
50 306
1027 4236
199 564
38.5 34.0
36 167
0.37
96 264
1821 3497
250 523
38.6 33.1
66 139
1.48
53 37
1218 536
222 153
44.0 31.2
45 19
1.94
17 374
492 5026
87 643
46.9 32.8
18 193
3.36
20 74
239 1582
75 241
27.1 41.7
9 57
1.64
108 277
2312 3188
412 425
42.3 30.1
76 135
5.56*
235 161
3794 1696
523 312
37.6 26.6
148 64
4.23*
45 350
688 4875
170 586
36.8 33.3
24 189
0.24
22 291
401 3860
134 522
43.2 32.8
13 154
1.38
30 345
312 4928
107 597
28.3 34.1
12 190
0.72
91 258
1400 3651
262 513
35.3 34.1
52 140
0.06
36 353
611 4841
154 613
38.4 33.0
23 185
0.81
67 312
1454 3968
225 490
43.0 31.6
50 159
3.56*
* p < .05.
HPV, human papillomavirus; HIV, human immunodeficiency virus.
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Table 3. Characteristics of Students Who Received the HPV Vaccine (Reference group = No)
Sex (reference group= boys) Race (reference group= other) White Black Asian Ever been tested for HIV Used a condom during last intercourse Age (reference group= 15years and younger)
Table 4. Characteristics of Students Willing to Receive the HPV Vaccine (Reference group = No)
OR
95% Confidence Interval
p
3.12
2.03-5.02
Correlates to Human Papillomavirus Vaccination Status and Willingness to Vaccinate in Low-Income Philadelphia High School Students Sarah B. Bass, PhD, MPHa Amy Leader, DrPHb Michelle Shwarz, PhD, MSEdc Judith Greener, MAd Freda Patterson, PhD, MSe
ABSTRACT BACKGROUND: Little is known about the correlates of human papillomavirus (HPV) vaccination or willingness to be vaccinated in urban, minority adolescents. METHODS: Using responses to the 2013 Youth Risk Behavior Survey in Philadelphia, a random sample of high schools provided weighted data representing 20,941 9th to 12th graders. Stratified by either having had or willingness to have the vaccine, bivariate analysis with sexual behavior, preventive health behaviors, mental health, substance use, and demographic characteristics were examined and then multivariable regression models were developed to estimate significant correlates. RESULTS: Respondents were 52.3% female, 84.4% non-White, and 65.9% ≥16 years; 43% reported having had the HPV vaccine, and of those not vaccinated, 66% reported willingness to be vaccinated. Logistic regression models indicate that females (odds ratio [OR] = 3.12, p < .01) and those reporting human immunodeficiency virus (HIV) testing (OR = 2.10, p < .01) were more likely to be vaccinated. Those reporting condom use during last intercourse (OR = 0.40; p = .05) and current marijuana use (OR = 0.37; p = .03) were less likely to indicate willingness to be vaccinated. CONCLUSIONS: Important areas for intervention include addressing misconceptions or feelings of ‘‘immunity,’’ especially for those using condoms. Understanding the correlation between HIV testing and HPV vaccination is also an important intervention opportunity for schools hoping to increase adolescent vaccination rates. Keywords: human papillomavirus; HPV; HPV vaccination: Youth Risk Behavior Survey; adolescent health; sexual health. Citation: Bass SB, Leader A, Shwarz M, Greener J, Patterson F. Correlates to HPV vaccination status and willingness to vaccinate in low-income Philadelphia high school students. J Sch Health. 2015; 85: 527-535. Received on June 30, 2014 Accepted on January 9, 2015
H
uman papillomavirus (HPV) is the most common sexually transmitted infection (STI) in both sexually active young adults and adolescents.1 It causes approximately 70% of cervical cancer cases2 in women and is regarded as the primary cause of anal, penile, and oral cancers in men.3 Experimental and epidemiological data suggests that HPV is the second most common risk factor for cancer development in humans, exceeded only by tobacco use.4 While death rates for the majority of cancers continue to
decline for men and women in the United States, incidence rates for HPV-related cancers, particularly oropharynx and anal, have increased substantially.5 This is especially true in minority men and women, who have either higher rates of HPV related cancers or higher mortality.5,6 Besides its oncogenic properties, HPV is also associated with 90% of the more than 500,000 cases of genital warts,7,8 making it a key target for public health intervention. In 2006 the Food and
a
Associate Professor, ([email protected]), Department of Public Health, Temple University, 1301 Cecil B. Moore Avenue, 9th Floor, Philadelphia, PA 19122. Assistant Professor, ([email protected]), Department of Medical Oncology, Division of Population Science, Thomas Jefferson University, 834 Chestnut Street, Suite 314, Philadelphia, PA 19107. c Research Assistant, ([email protected]), Department of Public Health, Temple University, 1301 Cecil B. Moore Avenue, 9th floor, Philadelphia, PA 19122. d Research Assistant, ([email protected]), Department of Public Health, Temple University, 1301 Cecil B. Moore Avenue, 9th floor, Philadelphia, PA 19122. e Assistant Professor, ([email protected]), Department of Public Health, Temple University, 1301 Cecil B. Moore Avenue, 9th floor, Philadelphia, PA 19122. b
Address correspondence to: Sarah B. Bass, Associate Professor, ([email protected]), Department of Public Health, Temple University, 1301 Cecil B. Moore Avenue, 9th Floor, Philadelphia, PA 19122. Funding was provided by Centers for Disease Control and Prevention, # 1U87PS004152-01.
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Drug Administration licensed quadrivalent human papillomavirus vaccine for use in girls and 2009 in boys and the Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices now recommends vaccination for HPV in both adolescent boys and girls at ages 11 or 12 as part of the regular vaccination schedule.9,10 As a result, research indicates that between 2006 and 2010, the prevalence of HPV-targeted infections decreased by more than half in adolescent girls,11 with HPV vaccination rates doubling from 25.1% in 2007 to 53.0% in 2011. However, 2012 vaccination initiation rates failed to increase significantly for girls.12 Similarly, rates of HPV vaccination among age-eligible boys, despite the new guidelines, are also suboptimal, ranging from just 2% to 20% in most survey samples.12,13 Geographic disparities in HPV vaccination rates have also been documented, indicating that poorer counties and families with lower income and levels of education have higher female vaccination rates, possibly because poorer areas tend to have more subsidized resources for health care services.14 This is reflected in the Philadelphia area. The National Immunization Survey-Teen (NIS-Teen) showed that in 2012, 13- to 17-year-old male and female adolescents in Philadelphia county had higher rates of vaccination than teens across the state of Pennsylvania and nationally.15 However, the NIS-Teen did not explore predictors of vaccination uptake or intention to vaccinate. Understanding the correlates of HPV vaccine uptake in both boys and girls, especially urban, at-risk adolescents, can help inform opportunities to increase vaccination rates. Previous research has shown that accessing health care, especially for sexual and mental health issues, is a predictor of HPV vaccine uptake.16 However, little is known about HPV vaccine uptake and willingness to receive the vaccine in high-risk, low-income urban adolescents. Most recent literature has focused on vaccination barriers among parents, or compared parent and child perceptions of vaccination.17-19 The majority of these have been with parents of female children16,20-22 and few have been done in urban, largely minority low-income groups.19 The few that have examined urban and/or minority groups have had small sample sizes, sampled only from 1 location and only focused on either girls and their parents or boys and their parents.21,23-26 In addition, while there have been a few larger sample studies,27 most have not examined health behaviors other than sexual behaviors as predictive correlates of being vaccinated or willingness to be vaccinated, have included only girls and have not focused on a large urban area. This study fills this gap by examining self-reported behaviors of Philadelphia high school students as part of the Youth Risk Behavior Survey (YRBS). Following is a report of 528 •
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correlates in both male and female students for having received the HPV vaccine or willingness to receive the vaccine in a weighted sample. No other YRBS has asked specifically about HPV vaccination, so results substantially add to the literature and can inform the development of proposed interventions in urban areas.
METHODS Participants The School District of Philadelphia oversees the YRBS survey in Philadelphia, with Temple University conducting the survey and analyzing data as the subcontractor. A 2-stage, cluster sample design is used to produce a representative sample of students. In the first stage, schools are selected with probability proportional to school enrollment size. In the second stage, intact classes of a required subject or intact classes during a required period are then selected randomly. Schools are contacted and instructed on what classes have been chosen to participate. All students in sampled classes are eligible to participate.28 If the survey’s response rate is at least 70%, samples can be weighted for data analysis. For this analysis, all high schools randomly selected in the Philadelphia School District (N = 32) participated. The student response rate was 71% (1280/1804). The study population included 1080 students, weighted to a population estimate of 20,941 to account for oversampling of minority groups. Instrument The YRBS is a biennial, self-administered survey of US high school students, administered at the national level by CDC and by states, territories, tribal areas, or large urban school districts; it is conducted during February to May of each oddnumbered year.28 Conducted since 1991, the surveys include representative samples of students in grades 9-12 and monitor 6 categories of priority health-risk behaviors.28 The standard 2013 YRBS questionnaire includes 5 demographic questions, 23 questions related to unintentional injuries and violence, 10 on tobacco use, 18 on alcohol and other drug use, 7 on sexual behavior, 16 on body weight and dietary behaviors, 5 on physical activity, and 2 on other health-related topics, such as asthma and sleep.28 (The 2013 questionnaire is available at http://www.cdc.gov/yrbss) Sites can also modify the standard questionnaire within certain parameters. Two thirds of the original questions must be retained and no more than 8 additional questions with mutually exclusive answers can be added. In addition, no more than a total of 99 questions can be included, to ensure that the questions can be completed in a single class period by all students.28 While sites can choose from
© 2015, American School Health Association
a list of optional questions, we received permission to include 2 new questions related to HPV vaccination, which has not been done in any other YRBS survey. Specific questions were: ‘‘Have you ever had the HPV vaccine?’’ (0 = no, 1 = yes) and ‘‘If your doctor recommended the HPV vaccine, would you get it?’’ (0 = no, 1 = yes). These outcome measures were then used in analysis with independent variables, including demographic characteristics, sexual health behaviors, mental health outcomes, and other health behaviors. For the question related to willingness to vaccinate, students who indicated that they had already been vaccinated (ie, any student who answered ‘‘yes’’ to ‘‘Have you ever had the HPV vaccine?’’) were excluded. Specific study variables are listed in Tables 1 and 2. Procedure Parental permission is obtained before administering the YRBS, according to each school district’s requirements. Trained data collectors travel to each school and administer the surveys using a standardized script and record the grade level of the class and number of students enrolled. All answers are anonymous and voluntary and students complete the self-administered questionnaire during 1 class period, recording their responses on a computerscannable answer sheet.28 All policies and procedures are approved through the Temple University Institutional Review Board. Data Analysis Statistical analyses were conducted on weighted data using the complex samples module of SPSS, version 20. Descriptive statistics and F tests were used to examine the demographic and health behavior characteristics of the sample for both outcome variables. Variables associated with these outcomes at the p ≤ .20 level were entered into multivariable regression models to estimate significant correlates for each independent association. Sampling errors were calculated through Taylor series linearization. Sampling weights were used to adjust for nonresponse and oversampling. Significance values of .05 were used to assess effect.
RESULTS Participant Characteristics The weighted sample was 52.3% female. Over half the sample was African American (56.2%), while 15.6% was Caucasian, 6.7% Asian, and the remaining 21.5% from another racial group. The sample was evenly distributed across grade levels: 28.3% was in 9th grade, 24.8% in 10th grade, 25.1% in 11th grade, and 21.5% in 12th grade. Journal of School Health
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Correlates of Having Received the HPV Vaccination Overall, 42.9% of the sample reported having received the HPV vaccine. Age, sex, and race were all significantly associated with being vaccinated. Specifically, a greater proportion of girls as compared with boys (53.4% vs 31.4%; Fadj = 60.71, p ≤ .001) and students ≥16 years as compared with ≤15 years (46.5% vs 36.0%; Fadj = 7.44, p ≤ .01) were vaccinated. A significantly smaller proportion of Asian (20.5%) as compared with White (47.5%), Black (43.6%), and students from ‘‘other’’ (44.8%) racial groups had been vaccinated (Fadj = 6.12, p < .01). Sexual health variables that were correlated with having received the HPV vaccine included having been tested for human immunodeficiency virus (HIV), having had sex with at least 4 people and being currently sexually active. Higher proportions of students who had been tested for HIV (55.3% vs 33.6% who were not tested; Fadj = 41.11, p ≤ .01), reported having sex with ≥4 people in their lifetime (52.5% vs 40.2% who had not; Fadj = 6.08, p = .02), and who reported having sex with ≥1 people in the last 3 months (52.7% vs 36.9% who had not; Fadj = 29.36, p ≤ .01) reported being vaccinated for HPV. Other health behaviors were also found to be correlated with vaccination. A greater proportion of students who had considered suicide in the last year reported having had the vaccine (51.1% vs 43.8% of students who had not; Fadj = 5.15, p ≤ .05). In addition, several current substance use variables were found to correlate with HPV status. A greater proportion of students who reported current alcohol use (52.2% vs 36.3% who did not currently drink; Fadj = 31.06, p ≤ .01), current binge drinking (59.2% vs 39.4% who did not report current binge drinking; Fadj = 25.03, p ≤ .01), and current marijuana use (51.3% vs 41.1% who did not report current marijuana use; Fadj = 13.18, p ≤ .01) were vaccinated. To identify independent correlates of receiving the HPV vaccine, a multivariable logistic regression model was estimated. Variables associated with having received the HPV vaccine at the p < .2 level were included and the Odds ratio, 95% confidence interval, and Bonferroni significance level reported (Table 3). Results showed that girls had a 3-fold greater likelihood of being vaccinated than boys (odds ratio [OR] = 3.12, p < .01), while students who reported being tested for HIV also had a 2-fold greater likelihood of being vaccinated for HPV (OR = 2.10, p < .01). These associations were adjusted for race, use of condom during last intercourse and age. Correlates of Willingness to Receive or Not Receive the HPV Vaccination Among students who reported not having had the HPV vaccine, 66.2% (population estimate of 10,982
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Table 1. Correlates of Having Received the HPV Vaccine Yes Variable
Estimate
SE
No %
N
Demographics Sex Girls 8111 731 53.4 327 Boys 4353 422 31.4 143 Age (years) ≤15 ≤15 3559 640 36 ≥16 ≥16 8905 845 46.5 Race White 2158 474 47.5 74 Black 7109 959 43.6 224 Asian 396 85 20.5 26 Other 2802 317 44.8 146 Grade 9th 2830 738 34.4 77 10th 3153 529 43.8 149 11th 3328 666 45.7 137 12th 3095 656 49.5 105 Other 59 42 72.6 2 Sexual health Had sex for the first time before 13years of age Yes 1132 261 42.4 34 No 10,241 814 42.6 401 Had sex with ≥4 people in their life Yes 2949 410 52.5 102 No 8375 661 40.2 330 Students who had sex with ≥1 people in the last 3months Yes 5253 591 52.7 186 No 6170 621 36.9 250 Among sexually active students, used a condom during last intercourse Yes 2640 440 48.8 94 No 2368 267 57.9 84 Been pregnant or had gotten someone pregnant ≥1 Yes 1242 257 54.2 42 No 11,058 1017 41.9 423 Used alcohol or drugs before last intercourse Yes 1198 258 57.5 37 No 3968 417 51.1 145 Has ever been tested for HIV Yes 6751 639 55.3 237 No 5350 590 33.6 219 Mental health Mental health not good for at least 1day in the last 30days Yes 7218 701 41.7 284 No 5133 506 44.6 183 Ever considered suicide Yes 1955 263 51.1 72 No 10,352 837 41.4 393 Ever attempted suicide Yes 972 167 51.2 36 No 9162 858 43.8 354 Current substance use (≥1 use in last 30days) Tobacco Yes 889 163 44.7 35 No 10,720 862 42.6 407 Alcohol Yes 4335 384 52.2 161 No 6098 548 36.3 240 Binge drinking Yes 2305 290 59.2 88 No 9505 775 39.4 360 Marijuana Yes 3557 456 51.3 127 No 8411 596 40.1 327
Estimate
SE
%
46.6 68.6
125 345
6337 10,240
2384 9200 1539 3454
527 1249 277 407
52.5 56.4 79.5 55.2
78 272 90 170
6.12
5400 4044 3960 3153 22
1399 813 764 853 22
65.6 56.2 54.3 50.5 27.4
148 189 162 110 1
3.12*
1538 13,788
171 1582
57.6 57.4
50 517
0.001
2668 12,450
333 1540
47.5 59.8
86 473
6.08*
4715 10,555
434 1380
47.3 63.1
162 403
29.36**
2767 1720
359 317
51.2 42.1
98 56
1.83
1048 15,309
205 1631
45.8 58.1
35 567
3.51
883 3790
198 408
42.5 48.9
29 131
0.61
5462 10,589
557 1306
44.7 66.4
184 412
41.12**
10,087 6385
1187 673
58.3 55.4
383 225
0.97
1872 14,652
333 1366
48.9 58.6
69 539
5.15*
928 11,779
205 1356
48.8 56.2
35 445
1.29
1102 14,456
253 1511
55.3 57.4
42 535
0.10
3969 10,695
588 1160
47.8 63.7
143 398
31.06**
1591 14,650
305 1469
40.8 60.6
59 538
25.03**
3380 12,539
397 1443
48.7 59.9
117 471
13.18**
HPV, human papillomavirus; HIV, human immunodeficiency virus.
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August 2015, Vol. 85, No. 8 •
60.71**
991 871
1364 1039
© 2015, American School Health Association
285 325
Adjusted F
7065 9513
** p ≤ .01; * p ≤ .05.
530 •
N
64 53.5
7.44**
Table 2. Correlates of Willingness to Get the HPV Vaccine Yes Variable
Estimate
SE
No %
Demographics Sex Girls 4587 757 64.9 Boys 6395 628 67.2 Age (years) ≤15 4127 861 65.1 ≥16 6856 853 66.9 Race White 1662 434 69.7 Black 6115 902 66.5 Asian 1038 209 67.5 Other 2167 278 62.7 Grade 9th 3495 886 64.7 10th 2486 507 61.5 11th 2970 615 75.0 12th 2009 604 63.7 Other 22 22 100 Sexual health Had sex for the first time before 13years of age Yes 986 152 64.1 No 8993 1130 65.2 Had sex with ≥4 people in their life Yes 1641 321 61.5 No 8214 1119 66.0 Students who had sex with ≥1 people in the last 3months Yes 2894 379 61.4 No 7058 961 66.9 Among sexually active students, used a condom during last intercourse Yes 1549 272 56.0 No 1184 242 68.8 Been pregnant or had gotten someone pregnant ≥1 Yes 556 180 53.1 No 10, 283 1167 67.2 Used alcohol or drugs before last intercourse Yes 644 198 72.9 No 2208 330 58.3 Has ever been tested for HIV Yes 3150 344 57.7 No 7400 1003 69.9 Mental health Mental Health not good for at least 1day in the last 30days Yes 6293 836 62.4 No 4689 558 73.4 Ever considered suicide Yes 1184 273 63.2 No 9776 969 66.7 Ever attempted suicide Yes 527 148 56.8 No 7919 951 67.2 Current substance use (≥1 use in last 30days) Tobacco Yes 791 193 71.7 No 9528 1070 65.9 Alcohol Yes 2570 439 64.7 No 7045 802 65.9 Binge drinking Yes 980 214 61.6 No 9809 1064 67.0 Marijuana Yes 1926 362 57.0 No 8571 1085 68.4
N
Estimate
SE
%
N
Adjusted F
184 212
2477 3118
322 477
35.1 32.8
101 113
0.28
129 267
2210 3385
589 375
34.9 33.1
72 142
0.15
53 177 62 104
722 3085 501 1287
157 526 124 187
30.3 33.5 32.5 37.3
25 95 28 66
0.44
94 117 118 66 1
1904 1558 989 1144
588 383 197 340
35.3 38.5 25.0 36.3
54 72 44 44
1.55
29 332
552 4794
133 612
35.9 34.8
21 185
0.03
50 306
1027 4236
199 564
38.5 34.0
36 167
0.37
96 264
1821 3497
250 523
38.6 33.1
66 139
1.48
53 37
1218 536
222 153
44.0 31.2
45 19
1.94
17 374
492 5026
87 643
46.9 32.8
18 193
3.36
20 74
239 1582
75 241
27.1 41.7
9 57
1.64
108 277
2312 3188
412 425
42.3 30.1
76 135
5.56*
235 161
3794 1696
523 312
37.6 26.6
148 64
4.23*
45 350
688 4875
170 586
36.8 33.3
24 189
0.24
22 291
401 3860
134 522
43.2 32.8
13 154
1.38
30 345
312 4928
107 597
28.3 34.1
12 190
0.72
91 258
1400 3651
262 513
35.3 34.1
52 140
0.06
36 353
611 4841
154 613
38.4 33.0
23 185
0.81
67 312
1454 3968
225 490
43.0 31.6
50 159
3.56*
* p < .05.
HPV, human papillomavirus; HIV, human immunodeficiency virus.
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© 2015, American School Health Association • 531
Table 3. Characteristics of Students Who Received the HPV Vaccine (Reference group = No)
Sex (reference group= boys) Race (reference group= other) White Black Asian Ever been tested for HIV Used a condom during last intercourse Age (reference group= 15years and younger)
Table 4. Characteristics of Students Willing to Receive the HPV Vaccine (Reference group = No)
OR
95% Confidence Interval
p
3.12
2.03-5.02
