A total of 11 studies were included in the review; one randomised controlled trial (RCT; 6,944 digital mammography images and 16,985 film mammography images), three paired studies (53,179 digital mammography images and film mammography images) and seven cohort studies (130,199 digital mammography images and 568,184 film mammography images).
Pooled data from all 11 studies indicated a higher rate of cancer detection with digital mammography than with film mammography (RR 1.17, 95% CI 1.06 to 1.29, I²=19%). Results were similar for the seven cohort studies and the single RCT, but the pooled estimate derived from the three paired studies showed no significant difference in cancer detection rates between the two screening methods.
There was high between-study heterogeneity in patient recall rate (Ι²=96%) and meta-analysis showed no significant difference in recall rate between the two screening methods. The RCT showed a higher recall rate in patients who underwent digital mammography (RR 1.69, 95% CI 1.46 to 1.96).
Invasive carcinoma detection rates and in situ carcinoma detection rates were similar between the two screening methods, for studies that reported this information (one RCT and six cohort studies).
Subgroup analysis, using data from three cohort studies, indicated that digital mammography was better than film mammography for detecting tumours in participants between 50 and 60 years of age (RR 1.23, 95% CI 1.05 to 1.44, I²=0%); no significant differences were found for participants older than 60 years of age. The RCT found that digital mammography was more effective in patients over 50 years, (RR 1.58, 95% CI 1.02 to 2.46), but not in patients between 45 and 49 years of age.