Personal factors influence use of cervical cancer screening services: epidemiological survey and linked administrative data address the limitations of previous research

Cancer of the cervix is the second most prevalent cancer among women worldwide. The greatest burden occurs in the developing world where the mortality rate ranges from 10 to 35 per 100 000 compared with two to four deaths per 100 000 in developed nations [1]. This difference is attributed to effective, national screening programs of cervical cytologic testing (the Papanicolaou test) to identify cell abnormalities that may indicate or precede cervical cancers [2, 3].

Screening programs for cervical cancer typically target all asymptomatic women from soon after the onset of sexual activity to early old age. Australia's National Cervical Screening Program recommends screening every two years, one to two years after the onset of sexual activity, until the age 70 [4]. This guideline remains despite the introduction of the human papillomavirus (HPV) vaccine, which cannot prevent all types of HPV that can cause cervical cancer [5]. Despite the success of such programs, inequalities in the receipt of screening services continue amongst women at greater risk of poor health outcomes [6‐8]. Consequently, researchers have attempted to identify women who are less likely to participate in screening to better target these services. These studies have reported that non participation is associated with being: single, sexually inactive, obese, a current smoker, uninsured, a non-metropolitan resident, having a low household income, lower level of education, current psychological distress, non-Caucasian background and attitudinal factors [8‐17]. Collection of sociodemographic information to aid in identifying inequitable access has been advocated [8].

The accuracy of service use data alongside personal information is central to ability of such research to inform service delivery in a meaningful way. Former studies into the inequalities in cervical cancer screening and other preventative health services have used one of two approaches: (1) self-reported service use or (2) administrative records. Each of these approaches has strengths and weaknesses. Self-report methods have the advantage of being collected alongside the detailed personal information that is needed to investigate the determinants of screening participation and exclude people who are ineligible for the service (e.g., those who have had a hysterectomy; [18]). The accuracy of self-reported health service use is, however, subject to bias associated with social desirability [19], 'over-reporting' [18, 20], inaccurate recall for the date of screening [20] and conflation with other health services [21] [though see: [22]]. There is typically only moderate concordance between self-report and medical records [19, 23, 24]. Importantly, discordance appears to be greater amongst women who are also less likely to receive cervical cancer screening [25‐27]. Administrative data is considered accurate but lacks concurrent data on the personal characteristics that may drive or inhibit service use. The small number of studies that have combined personal and administrative data have been limited to unrepresentative samples such as primary health care settings that may exclude women who do not frequent health services [28].

The Personality and Total Health Through Life Study (PATH) uses a cross-sequential design to examine adult development with three representative, general community cohorts. These cohorts were aged 20-24, 40-44 and 60-64 years at baseline with follow-up every four years [29, 30]. In addition to collecting comprehensive self-reported health and psychosocial data, over 90% of participants gave permission for their administrative health service records to be accessed.

This study addresses several methodological limitations of previous research into the determinants of cervical cancer screening and other preventative health services by combining the strengths of self-report and administrative approaches. We link self-reported psychosocial data with administrative records for screening service use. By doing so we are able to (1) estimate the rates of cervical cancer screening, (2) verify the characteristics thought to be associated with cervical cancer screening, (3) investigate whether these characteristics vary with women's age, and (4) quantify the effects of these inequalities with greater reliability.

Table 1 analyses are based on data from 1141 women in the middle-aged cohort and 954 women in the older-aged cohort (N = 2095). The remaining analyses exclude women who report hysterectomy (n = 146 in middle-aged and n = 267 in the older cohort), resulting in a total sample of 1685 women. Table 1 reports the characteristics of the sample, presenting weighted and unweighted estimates and the proportion of missing data for each measure. It is evident that missing data is relatively rare, with only the measures of BMI, exercise and the RAND-12 physical functioning scale having over 2% missing data. The majority of women in the study have children, are married and are Caucasian. Welfare reliance and financial hardship are rare, though almost half of the sample is not participating in the workforce (reflecting the norm for the older cohort).

Table 2 contrasts the estimates of two-year cervical cancer screening derived from the PATH sample (excluding women who have had a hysterectomy) with comparable administrative data for the Australian Capital Territory. The estimates from the PATH survey are within or on the cusp of the 95% confidence interval.

Results from analyses of the correlates of screening participation are presented in Table 3. Women in the younger cohort, those who had children, those with a partner and those with higher levels of overall Medicare service use were more likely to participate in cervical cancer screening. Within the socio-economic measures, being reliant on government welfare payments, living in rental housing and not working were associated with lower likelihood of participating. For lifestyle factors: the odds of screening participation were lower for women who were obese and current smokers, and higher for women who reported use of illicit drugs (marijuana, ecstasy or amphetamines) during their lifetime. Experience of sexual abuse in childhood was associated with lower rates of cervical cancer screening. None of the measures of personality were significantly associated with screening participation. Finally, poor self-rated health, lower levels of physical functioning and anxiety and depression symptoms were also associated with lower rates of screening.

Model B in Table 3 presents the significant independent correlates of cervical cancer screening in accordance with Australian guidelines. These factors were: younger age, having had children, having a partner, higher overall use of Medicare services, not being welfare reliant, being employed, not being obese, not being a current smoker, a reported history of drug use, not reporting childhood sexual abuse, higher levels of physical functioning, and not reporting symptoms of anxiety. Odds ratios for all non-significant, univariate variables listed in Model A were also calculated with adjustment for the factors included in the final multivariate Model B model (see Additional file 1: Table S1). These variables remained non-significant following this adjustment.

Model B was replicated without adjustment for overall health service use to address concerns that this covariate may confound a model for cervical screening service use given that the former is causally related to the latter (see Model C, Table 3). The estimates for Model C are comparable to Model B, indicating that adjustment for overall service use had minimal impact on sociodemographic and personal predictors of cervical screening specifically. Two variables, age cohort and physical functioning, were no longer significantly associated with cervical screening when overall health service use was not controlled. This indicates that the associations between these two characteristics and cervical screening may only be revealed when the higher rates of overall health service use of older women and those with poorer physical functioning are accounted for. Repeating all models with unweighted and imputed data replicated the findings.

We examined the factors associated with women's participation in cervical cancer screening services in accordance with national guidelines using linked survey and administrative data. Overall, cervical screening participation rates were consistent with relevant administrative statistics, with around 60% of women having been screened over a two year period. In order of the strength of association, the independent predictors were high and moderate overall health service use, not reporting childhood sexual abuse, younger age, non-smoking, having children, no/low levels of anxiety symptoms, lifetime reported drug use, not being welfare reliant, being employed, not being obese, and high levels of physical functioning. To illustrate the implications of these findings, we used PAR to quantify the level of non-participation in screening that reflected inequalities associated with characteristics likely to be known by a woman's clinician. Approximately 75% of non-participation in cervical cancer screening within the recommended two-year period was attributable to these observable risk-factors; or 50% of non-participation if overall health service use was not accounted for. It is unrealistic to expect that, in a clinical setting, all of these demographic, socio-economic, lifestyle, trauma and health risk barriers to screening can be totally and concurrently resolved so that screening participation rates exactly aligned with the guidelines. Individual autonomy, broader life circumstances, and the multiple demands placed on clinicians are additional factors that will influence whether these risk factors can be modified and how much. However, this finding does demonstrate the potential gains that could be achieved from intervention efforts to address the identified inequalities in screening and effective targeting of health promotion messages.

This study illustrates a leading and reliable approach to investigating the personal and social determinants of health service use by exploiting the complementary strengths of individual survey and administrative data. Inequalities in cervical cancer screening exist despite the universality and subsidised costs of cervical cancer screening in Australia. Together with existing knowledge about factors that contribute to general health service use amongst women [51, 52], the findings of this study offer an important contribution to health promotion efforts for the uptake of cervical screening services. Our results indicate that programs to improve screening uptake amongst women who are currently less likely to participate should focus on those who are not working, reliant on social welfare, currently smoke, do not have children, have poorer physical functioning, high levels of anxiety, a history of sexual abuse and low overall levels of health service use. The importance of such action is emphasised by the fact that some of these characteristics are known risk factors for the development of cervical cancer [53].