There were 129 participants (all men) allocated to the Prosdex intervention group in the associated RCT [17
]. Of these, 82 successfully viewed Prosdex and had web-logs available for analysis. Web-logs were not available for 47 participants: 30 of the 47 did not attempt to access the site, and 17 attempted to access the site but then encountered software problems (eg, were unable to install Flash media player).
For 8 of the 82 men who successfully viewed Prosdex, we found an excessive amount of time spent viewing particular pages, indicating that these men had likely left the computer on for long periods of time with no interaction (in one case this was 11 days). Viewing times for these participants distorted the mean amount of time spent on each page, section, module, as well as the site as a whole, and were therefore excluded from descriptive analyses relating to time.
Of the 82 men whose web-logs indicated that they had successfully viewed Prosdex, 73 completed the online questionnaire and provided complete outcome data. Data for these 73 men were included in correlation analyses. The 17 men who attempted to access the Prosdex site but were unsuccessful (therefore providing no web-log data) had, however, completed the online questionnaire and provided complete outcome data. These men were compared with the 73 men who successfully accessed the site and who had complete outcome data.
presents participant characteristics of the sample. Most men were between 50 and 59 years of age, married or living as married, and white. In addition, 36 out of 82 (44%) had a graduate or postgraduate qualification.
Participants’ characteristics (n = 82)
presents a summary of the outcomes relating to participants’ use of Prosdex and the 3 modules: “The PSA Test,” “It’s Your Choice,” and “Prostate Cancer.” presents a summary of the outcomes relating to participants’ use of the interactive features, including videos and animations.
A summary of participants’ use of Prosdex: mean time (seconds); mean number of pages viewed; percentage of available pages viewed and percentage of videos/animations viewed among men in the low, intermediate, and high access groups
A summary of participants’ use of video clips and animations on Prosdex among men in the low, intermediate, and high access group
Participants (n = 74, outliers excluded) spent a mean of 20 (SD 15) minutes on Prosdex. The shortest time spent on Prosdex was 1 minute and the longest time was 61 minutes. Participants spent a mean of 7 (SD 5) minutes on the “The PSA Test” module, a mean of 4 (SD 4) minutes on the “It’s your Choice” module, and a mean of 7 (SD 7) minutes on the “Prostate Cancer” module. The longest time spent on each module was 23 minutes, 17 minutes, and 30 minutes respectively. The relatively large standard deviations obtained highlight the large variability in the time that men spent on the modules.
The participants (n = 82) viewed a mean number of 32 (SD 21) out of a possible 60 main content pages on the Prosdex site with only seven men (8.5%) viewing all 60. A mean of 11 (SD 6) pages out of 19 were viewed from the “PSA Test” module. Eight men (10%) viewed all 19 pages while four men (5%) did not view any pages from this module. A mean number of nine (SD 8) pages out of 19 was viewed from the “It’s your Choice” module, with 17 men (20%) viewing all 19 pages, and 16 men (20%) not accessing any pages. A mean number of 12 (SD 9) pages out of 22 was viewed from the “Prostate Cancer” module. All 22 pages were viewed by 19 men (23%) while 13 men (16%) did not view any pages from this module. Overall, men spent longer and viewed more pages in the “PSA Test” and “Prostate Cancer” modules than they did in the “It’s Your Choice” module.
The interactive features of the site included videos and animations. The mean number of videos viewed was 1 out of 25, and the mean number of animations viewed was 1 out of 8. Of the 82 men, 64 (78%) did not view any video clips, and 44 (54%) did not view any animations. Of the 82 men, 37 (45%) used the “decision stacker,” designed to facilitate involvement in the decision making process. The majority of these men only used the stacker once, and therefore, usage was minimal. Only 3 men out of 82 (4%) used the integrated print functionality, printing only one item of information each.
Analysis to Identify Subgroups of Users
By examining the frequency distribution and Q-Q (quantile-quantile) plot of the number of pages accessed, we identified a bimodal distribution. The frequency distribution of number of pages accessed suggested two modes, at ≤ 40% and ≥ 80% of the pages, with a relative dearth of intermediate values. Therefore, we defined three groups in terms of the number of pages participants accessed: low access was defined as 0 to 40% (ie, 0 to 24 pages), intermediate access as 41 to 79% (ie, 25 to 47 pages), and high access as 80 to 100% (ie, 48 to 60 pages).
highlights the difference in overall Prosdex usage between the three groups and also demonstrates that the difference in usage was fairly consistent throughout each module and section of the website. Men in the low access group viewed a mean of 37% (7 out of 19 pages) of the “PSA Test” module, 5% (1 out of 19 pages) of the “It’s Your Choice” module, and 15% (3 out of 22 pages) of the “Prostate Cancer” module. On the other hand, men in the high access group viewed, on average, over 90% of the available pages in each module: 17 out of 19 pages of the “PSA Test” module, 18 out of 19 pages of the “It’s Your Choice” module, and 21 out of 22 pages of the “Prostate Cancer” module. shows that the use of videos and animations was low in all three groups, although the high access group viewed a greater percentage of available videos and animations than the low access group.
Correlations Between Usage and Components of Informed Decision Making
Correlations between usage (measured by number of pages accessed) and the measures of informed decision making were assessed (Spearman rank correlation [ρ], two-tailed). Focusing on number of pages as an indicator of usage allowed for the inclusion of participants with outliers on time data. There was a significant positive correlation between the total number of pages viewed and the overall knowledge score (ρ = 0.69, P < .001). In other words, the more pages a user accessed, the higher their knowledge score.
A negative correlation was found between the total number of pages viewed and attitude to screening (ρ = -0.52, P < .001). That is, the more pages the user accessed, the less favorable their attitude to the PSA test became. A negative correlation was also found between total number of pages viewed and intention to take the PSA test (ρ = -0.44, P < .001). In other words, the more pages the user accessed, the less likely their intention was to have the test.
Comparisons Between Groups
Significant differences were demonstrated in knowledge scores, attitudes towards the test, and intention to have the test between men who accessed less than 40% of the website and men who accessed 80 to 100%. Specifically, t test results demonstrated that those in the high access group (80 to 100%) had significantly higher knowledge scores (t56 = 6.35, P < .001), and significantly less favorable attitude towards the PSA test (t48 = -4.51, P < .001). There was also a significant and inverse effect of number of pages viewed on intention to have the test when comparing the high access and low access groups (Mann-Whitney U = 211, n
= 31, n
= 26, P < .001, two-tailed).
On comparing participants with successful and unsuccessful access to Prosdex, there were significant differences. Specifically, t tests demonstrated that those who were successful had significantly higher knowledge scores (t36 = 4.59 P < .001) and significantly less favorable attitudes towards the PSA test (t43 = -2.44 P = .02). There was no significant difference between the groups on intention to have the PSA test (Mann-Whitney U = 585.5, n
= 73, n
= 17, P = .71, two-tailed)