From January 2018 through February 2018, Indiana residents who had been seen at least once in the previous year at Indiana University Health (IU Health) participated in a cross-sectional, mail-based survey known as the Hoosier Health Survey. A statewide integrated health system, IU Health operates 19 hospitals in Indiana and 178 clinics that provide outpatient care. The purpose of this survey was to better understand the cancer control needs of the community served by the Indiana University Cancer Center. Following HIPAA authorization from respondents to access their electronic health records, cancer screening information obtained through the survey were matched with the participant’s longitudinal EHR data by referencing each patient’s first and last name, birthdate, and place of residence. The electronic information was obtained from the Indiana Network for Patient Care (INPC), which is the clinical data repository for IHIE, a community-wide HIE operating in central Indiana with the support of the Regenstrief Institute. The INPC consists of clinical observations across five major hospital systems, public health departments (both state and county), and Indiana Medicaid., The study was approved by the IUPUI Institutional Review Board.
Study cohort
From a list of 284,062 people seen at least once in the past 12 months in the statewide health system and living in one of 34 Indiana counties with higher cancer mortality rates, a random, stratified sample of 8,000 adults was selected. In stratifying the sample, geographic location and race were equally weighted. The initial goal was to sample 2,000 individuals from each of four strata (rural White, rural Black, urban White, urban Black); due to the small number of participants in rural Black, the remaining 2,000 were taken from the rural White strata, resulting in 4,000 individuals from both rural and urban areas. 21 patients were excluded from the sample because their primary care providers declined to authorize their participation in the survey, thus resulting in 7,979 mailed surveys. Out of all mailed surveys, a total of 970 adults aged 18–75 years completed the survey, generating a 12% response rate. Younger adults were included in the sample so as to collect data on cervical cancer screening behavior; the upper age limit of the sample was set at 75 years because guidelines do not routinely recommend cancer screening after age 75. Out of these 970 respondents, a total of 711 individuals provided HIPAA authorization (73.3%), comprising our final study sample. The survey methodology has been described in more detail elsewhere. [11]
Populations eligible for cancer screening
The participants in our study were assessed on their cancer screening behavior for three types of cancer: colorectal, cervical, and breast. Screening guidelines from the U.S. Preventive Services Task Force (USPSTF) were used to determine the sample of survey respondents eligible for appropriate screening tests. For colorectal cancer, the eligible sample included men and women aged 50–75 years to receive a Colonoscopy every ten years or receive a fecal immunochemical test (FIT)/stool test every year. For cervical cancer, the eligible sample included women aged 21–29 years to receive a Pap test every three years and 30–65 years to receive a Pap test every three years or a Human Papilloma Virus (HPV) test every five years. In the case of breast cancer, the eligible sample was taken from women aged 50–75 years to receive a Mammography every two years.
Survey-based cancer screening measures
When eligible for screening, the respondents were asked whether or not they reported receiving one of the three cancer screening approaches with responses being “Yes” or “No” (binary in nature). For colorectal cancer, patients were asked if they ever received a Colonoscopy and whether they had one every ten years, as well as if they ever received a Fecal Immunochemical Test (FIT)/stool test, and whether they had one every year. For cervical cancer, patients were asked if they ever received a PAP test and if they had one every three years, or if they ever received a Human Papilloma Virus (HPV) test and if they had one every five years. For breast cancer, the patients were asked whether they ever received a Mammogram and if they had one every two years.
Respondents were also asked the time since their last screening test with responses being “Within the past year (less than 12 months ago)”, “More than 1 year ago, but less than 2 years ago”, “More than 2 years ago, but less than 3 years ago”, “More than 3 years ago, but less than 5 years ago”, or “5 or more years ago” (ordinal in nature). See Appendix 1 for detailed survey questions. Information on receipt of the screening and time since last screening were measured to assess the degree of association and concordance between survey self-report and HIE data.
STATISTICAL ANALYSIS
Descriptive statistics were performed of individual socio-demographic characteristics, including age, gender, race, educational level, marital status, insurance status, income, home ownership, employment status, rurality based on RUCA codes, and self-reported health status.
For the questions on receipt of cancer screening and time since last screening, as a first step, we conducted bivariate analysis on participants’ responses to the survey and the corresponding information in HIE data using Chi-square tests to check for any significant differences between the two information sources. As a second step, we evaluated the association and concordance between the two measures of screening information. For the questions on time since last screening, we only considered those participants whose HIE data as well self-report indicated receipt of screening.
To measure the strength and direction of association between the two information sources of screening data (survey self-report and EHR from HIE) we used the Spearman’s rank correlation coefficient (ρ). The value of ρ ranges from − 1 to + 1, indicating a perfectly negative to a perfectly positive association, with 0 indicating no association at all., The effect sizes were interpreted according to Cohen's (1988) guidelines.
Finally, we used two interrater reliability measures to measure the concordance of screening information obtained from HIE data and survey self-report:
- A) Percentage Agreement, one of the most common interrater reliability measures, is calculated as the number of agreement scores divided by the total number of scores.
- B) The Gwet's agreement coefficient (Gwet's AC), a measure of correlation, is defined as the conditional probability that two randomly chosen observational measurements will agree, assuming no agreement by chance. The agreement coefficients were calculated using Gwet's new chance-corrected inter-rater agreement coefficients weighted ordinally, extending all existing agreement coefficients to include multiple raters, multiple rating categories, any measurement level, and multiple ratings per subject.
We chose Gwet’s AC as a measure of concordance over an alternative measure, Cohen’s Kappa, as the latter suffers from various statistical issues.,,,, The Gwet's AC is interpreted according to Landis and Koch's guidelines., The analyses were performed in Stata (Stata 16.1, StataCorp LLC, College Station, TX).
[1] Cohen/Conger’s Kappa (κ), similar to correlation coefficients ranging from -1 to +1 with 0 representing the amount of agreement expected from random choice, and 1 indicating perfect agreement is an alternative method to measure the level of concordance between raters [21]. We choose Gwet’s AC over Cohen’s Kappa as Cohen’s Kappa suffers from some statistical issues; it assumes independence between the raters, hence frequently generating agreement due to chance which is not entirely correct. However, the Gwet’s AC does not depend upon this assumption. Additionally, the Cohen’s Kappa values suffer from the “Kappa paradox”; they tend to change quite a lot with a change in prevalence, i.e., the values become high and close to the percentage agreement when there is high prevalence (the prevalence problem). Also, the degree to which observers disagree has an impact on the Kappa values (the bias problem). Gwet’s AC tends to lessen the kappa limitations;[22,23] hence we consider Gwet’s AC providing more stable inter-rater reliability coefficients in our study following few recent studies that have also preferred Gwet’s AC over Cohen/Conger’s Kappa for being a more stable inter-rater reliability coefficient.[24,25,26]