Assessing Cervical Cancer Screening Coverage Using a Population-Based Behavioral Risk Factor Survey

Abstract

Cervical cancer is the second most common cancer and fourth leading cause of cancer-related deaths among women in Thailand. In 2005, the Ministry of Public Health (MoPH) in Thailand initiated a phased national cervical cancer screening program. To monitor progress toward national screening targets—80% of women 30–60 years of age screened for cervical cancer once in the previous 5 years by 2013—the MoPH used the 2010 Thai Behavioral Risk Factor Surveillance System (BRFSS) to assess cervical cancer screening coverage. Results from the survey showed that 67.4% of women aged 30–60 years had been screened for cervical cancer in the past 5 years with varying screening coverage by region, residence, education, and marital status. Although the national cervical cancer screening program in Thailand appears to be close to reaching its national targets, the causes of lower coverage in some subpopulations need to be identified so that targeted interventions can be developed to increase coverage in these groups.

Introduction

In 2012, there were ∼530,000 new cases of cervical cancer and 266,000 deaths caused by cervical cancer worldwide; more than 85% of deaths occurred in less developed countries.¹ In Thailand, ∼8000 women are diagnosed with having cervical cancer each year. The cervical cancer incidence rate among women in Thailand (17.8 per 100,000) is similar to the rate among women in the southeastern Asia region (16.3 per 100,000).¹ In 2005, ∼25% of women 30–65 years of age had been screened for cervical cancer once in the past 5 years.²

In 2005, to reduce the burden of cervical cancer in Thailand, the National Health Security Office and Ministry of Public Health (MoPH) initiated screening for cervical cancer using Papanicolaou (Pap) tests in every province except Bangkok. In 2006, the program was expanded to include visual inspection with acetic acid (VIA) screening in 17 of the 75 provinces with Pap test screening. The Thai MoPH recommends a Pap test every 5 years for women aged 30–60 years or a VIA test every 5 years for women aged 35–49 years.² National targets for the percent of women aged 30–60 years screened for cervical cancer once in the previous 5 years were 20% in 2010, 60% in 2011, 70% in 2012, and 80% in 2013.³

In 2007, the Thai Behavioral Risk Factor Surveillance System (BRFSS) was introduced in 38 provinces using questions adapted from the US Centers for Disease Control's BRFSS.⁴ The Thai BRFSS was expanded in 2010 to include all 76 provinces in the country. The 2010 survey included the question, “When was the last time that you had cervical cancer screening?” to facilitate estimation of cervical cancer screening coverage in the population.

Methods

Survey participants were selected using a stratified two cluster design.⁵ Eligible Thai citizens aged 15–74 years were interviewed face-to-face by trained health interviewers. The proportion of respondents who reported having been screened for cervical cancer at least once in the preceding 5 years was calculated, overall, and by age and relevant demographic characteristics. Proportions with 95% confidence intervals (CIs) were estimated after weighting. Chi-square tests were used to assess differences in screening coverage by age, education, region, area (i.e., urban vs. rural), and family income. Differences between subgroups with a p-value <0.05 were significant.

Results

Five-year cervical cancer screening coverage

The overall cooperation rate was 84.7%. A total of 65,443 women aged 15–74 years responded to the survey; 61,905 (94.5%) answered the question about cervical cancer screening, including 36,086 women aged 30–60 years, the target group for screening. The proportion of women reporting as having been screened for cervical cancer in the past 5 years was 67.4% (95% CI = 66.2%–68.7%) among women in the target age group, 21.9% (95% CI = 20.6%–23.2%) among women aged 15–29 years, and 42.2% (95% CI = 40.3%–44.1%) among women aged >60 years (Table 1).

Table 1.

Proportion of Women Screened for Cervical Cancer in the Past 5 Years by Age Group—Thai BRFSS, 2010

Age (years)	Sample size (n)	Proportion (%)	95% Confidence interval
15–29	14,847	21.9	20.6–23.2
30–49	23,161	67.6	66.3–68.9
50–60	12,925	66.9	65.0–68.8
>60	10,942	42.2	40.3–44.1
Target 30–60	36,086	67.4	66.2–68.7
Total 15–74	61,905	51.7	50.7–52.8

BRFSS, Behavioral Risk Factor Surveillance System.

Women aged 30–60 years

Among women in the target age range for cervical cancer screening, 5-year screening percentage was lower in the Bangkok metropolis (37.4%; p ≤ 0.0001) and central (64.5%, p ≤ 0.0001) and southern (63.9%, p ≤ 0.0001) provinces (Table 2). Screening coverage was also lower among women with higher levels of education (59.2%, p ≤ 0.0001), women who resided in urban areas (56.4%, p ≤ 0.0001), and women who were widowed (64.6%, p = 0.0168) or never married (35.8%, p ≤ 0.0001). Screening coverage was similar across levels of family income.

Table 2.

Proportion of Women Aged 30–60 Years Screened for Cervical Cancer in the Previous 5 Years—Thai BRFSS, 2010

Characteristics	Sample size (n)	Proportion (%)	95% Confidence interval
Total	36,086	67.4	66.2–68.7
Education level
Grades 0–8	26,752	69.8	68.4–71.2
Grades 9–11	5302	61.6	58.6–64.5
Grade 12 and beyond	3702	59.2	56.2–62.2
Area
Urban	17,984	56.4	54.2–58.6
Rural	18,102	73.2	71.7–74.6
Region
Bangkok metropolis	491	37.4	31.4–43.4
Central	11,449	64.5	62.1–66.8
Northeast	9092	75.7	73.7–77.7
North	8571	73.9	71.7–76.0
South	6483	63.9	61.1–66.7
Marital status
Single	4098	35.8	33.0–38.7
Married	28,284	72.3	71.0–73.6
Divorced	1227	67.2	62.5–72.0
Widowed	2218	64.6	60.4–68.8
Family income (Baht)
<5000	5044	72.9	70.6–75.2
5000–9999	8388	72.8	71.0–74.5
10,000–24,999	10,838	68.2	66.3–70.0
≥25,000	5204	69.2	66.5–72.0

Discussion

Screening programs have substantially reduced the burden of cervical cancer in developed areas of the world; however, cervical cancer remains a leading cause of cancer-related deaths among women in low- and middle-income countries.⁶ In recent years, many countries have increased investment in cervical cancer screening to reduce the burden of this preventable disease. The World Health Organization recommends a variety of screening methods and algorithms, including Pap tests, VIA, and Human papillomavirus (HPV) testing, based on existing infrastructure, resources, and capacity.⁷ Cervical cancer screening coverage is a key indicator in the World Health Organization's global monitoring framework for ensuring progress on the control of noncommunicable diseases.⁸ Adequate screening coverage and appropriate follow-up of women at highest risk for developing cervical cancer are necessary to reduce mortality.⁷

The CDC BRFSS has been used to assess cervical cancer screening coverage in the United States since the 1980s.⁴ Monitoring screening coverage where organized national programs are still in development, or do not exist, is a major challenge. In these instances, population-based behavioral and risk factor surveys could become an increasingly important source of information about screening coverage and the demographic characteristics of screened and unscreened women.

Results of the 2010 Thai BRFSS presented in this report demonstrate a substantial increase in screening coverage since the initiation of the national cervical cancer screening program in 2005 and suggest that the national target for 5-year screening coverage among women aged 30–60 years (20% in 2010, 60% in 2011) has been reached thus far. The findings also highlight potential disparities in screening based on region, urban versus rural residence, education, and marital status. These disparities could be the result of a variety of possible factors, including differences in knowledge, awareness and beliefs, and access to care. Reasons for lower screening rates among specific subpopulations need to be further explored to develop effective targeted interventions to increase screening coverage.

This study has at least three limitations. First, screening status is based on responses to survey questions, not medical records. Reliance on self-reported data on screening might over- or underestimate actual screening because women might confuse a Pap test or VIA with another gynecological procedure.⁹ Second, the method by which respondents were screened (i.e., Pap vs. VIA) could not be discerned because of the wording of the survey question. However, this limitation did not preclude estimation of overall 5-year screening coverage for women in the target age group. Testing and validation of questions regarding cervical cancer screening could help to address these issues and ensure high data quality and comparability on subsequent BRFSS surveys in Thailand. Finally, these data do not provide information about whether women with abnormal screening test results were successfully linked to appropriate follow-up and treatment. Appropriate follow-up of women with positive screening test results is necessary to decrease mortality from cervical cancer.²

In summary, this report demonstrates the feasibility of using a population-based behavioral and risk factor survey to monitor a cervical cancer screening program. According to the 2010 Thai BRFSS, 67.4% of women aged 30–60 years were screened in the 5 years preceding the survey. Disparities in screening coverage by demographic characteristics were identified that warrant further exploration. Testing and validation of questions about cervical cancer screening could be considered in Thailand to ensure collection of high quality survey data.

What Is CDC Doing to Improve Cervical Cancer Screening in Low-Resource Settings?

CDC's Division of Cancer Prevention and Control collaborates with a variety of partners, including the World Health Organization, the American Cancer Society, the International Agency for Research on Cancer, and Ministries of Health to build capacity for cancer surveillance and cervical cancer screening programs in low-resource settings.

In addition to collaborations to assess cervical and breast cancer screening coverage in Thailand, CDC is also working with the Thai MoPH and Thai National Cancer Institute to assess whether HPV testing could improve the cost-effectiveness of screening programs in the northeastern province of Ubon Ratchathani. HPV testing and VIA require less infrastructure than Pap-based screening. These two methods also have the potential to increase screening coverage and follow-up in some areas by enabling fewer visits and, in the case of VIA, the possibility of screening and treatment of women for precancerous lesions in the same visit (i.e., screen-and-treat approach).

International collaborations allow CDC to share 20+ years of experience supporting the implementation and evaluation of a national Pap smear-based screening program for low-income and rarely or never screened women in the United States.¹⁰ It also enables CDC to learn from countries such as Thailand (a middle-income country) that are implementing alternative screening strategies and leveraging community health workers to increase coverage and follow-up of hard-to-reach women. For example, HPV testing and VIA might help to improve cervical cancer screening in lower-resource settings in the United States such as the US-Affiliated Pacific Island Jurisdictions (USAPIJ) where the distance between islands and the lack of laboratory infrastructure in many areas have made Pap smear-based screening exceedingly difficult to implement.¹¹

Footnotes

Acknowledgments

The authors acknowledge the support of colleagues in the Thai MoPH, Thai BRFSS, and the Thai National Cancer Institute.

Author Disclosure Statement

No competing financial interests exist.

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Assessing Cervical Cancer Screening Coverage Using a Population-Based Behavioral Risk Factor Survey—Thailand,2010