Rubén Román

Effect of protocol-related variables and women's characteristics on the cumulative false-positive risk in breast cancer screening

BACKGROUND Reducing the false-positive risk in breast cancer screening is important. We examined how the screening-protocol and womens characteristics affect the cumulative false-positive risk. METHODS This is a retrospective cohort study of 1565364 women aged 45-69 years who underwent 4739498 screening mammograms from 1990 to 2006. Multilevel discrete hazard models were used to estimate the cumulative false-positive risk over 10 sequential mammograms under different risk scenarios. RESULTS The factors affecting the false-positive risk for any procedure and for invasive procedures were double mammogram reading [odds ratio (OR)=2.06 and 4.44, respectively], two mammographic views (OR=0.77 and 1.56, respectively), digital mammography (OR=0.83 for invasive procedures), premenopausal status (OR=1.31 and 1.22, respectively), use of hormone replacement therapy (OR=1.03 and 0.84, respectively), previous invasive procedures (OR=1.52 and 2.00, respectively), and a familial history of breast cancer (OR=1.18 and 1.21, respectively). The cumulative false-positive risk for women who started screening at age 50-51 was 20.39% [95% confidence interval (CI) 20.02-20.76], ranging from 51.43% to 7.47% in the highest and lowest risk profiles, respectively. The cumulative risk for invasive procedures was 1.76% (95% CI 1.66-1.87), ranging from 12.02% to 1.58%. CONCLUSIONS The cumulative false-positive risk varied widely depending on the factors studied. These findings are relevant to provide women with accurate information and to improve the effectiveness of screening programs.Background: Reducing the false-positive risk in breast cancer screening is important. We examined how the screening-protocol and womens characteristics affect the cumulative false-positive risk. Methods: This is a retrospective cohort study of 1 565 364 women aged 45–69 years who underwent 4 739 498 screening mammograms from 1990 to 2006. Multilevel discrete hazard models were used to estimate the cumulative false-positive risk over 10 sequential mammograms under different risk scenarios. Results: The factors affecting the false-positive risk for any procedure and for invasive procedures were double mammogram reading [odds ratio (OR) = 2.06 and 4.44, respectively], two mammographic views (OR = 0.77 and 1.56, respectively), digital mammography (OR = 0.83 for invasive procedures), premenopausal status (OR = 1.31 and 1.22, respectively), use of hormone replacement therapy (OR = 1.03 and 0.84, respectively), previous invasive procedures (OR = 1.52 and 2.00, respectively), and a familial history of breast cancer (OR = 1.18 and 1.21, respectively). The cumulative false-positive risk for women who started screening at age 50–51 was 20.39% [95% confidence interval (CI) 20.02–20.76], ranging from 51.43% to 7.47% in the highest and lowest risk profiles, respectively. The cumulative risk for invasive procedures was 1.76% (95% CI 1.66–1.87), ranging from 12.02% to 1.58%. Conclusions: The cumulative false-positive risk varied widely depending on the factors studied. These findings are relevant to provide women with accurate information and to improve the effectiveness of screening programs.

Reduction in False-Positive Results after Introduction of Digital Mammography: Analysis from Four Population-based Breast Cancer Screening Programs in Spain

PURPOSE To evaluate the effect of the introduction of digital mammography on the recall rate, detection rate, false-positive rate, and rates of invasive procedures in a cohort of women from four population-based breast cancer screening programs in Spain. MATERIALS AND METHODS The study was approved by the ethics committee; informed consent was not required. A total of 242,838 mammograms (171,191 screen film [screen-film mammography group] and 71,647 digital [digital mammography group]) obtained in 103,613 women aged 45-69 years were included. False-positive results for any additional procedure and for invasive procedures, the breast cancer rate, and the positive predictive value in each group were compared by using Pearson χ(2) test. The effect of the mammographic technology used (screen-film or digital) on the false-positive results and cancer detection risk was evaluated with multivariate logistic regression models, adjusted according to womens and the screening programs characteristics and time trends. RESULTS The false-positive rate was higher for screen-film than for digital mammography (7.6% and 5.7%, respectively; P < .001). False-positive results after an invasive procedure were significantly higher for screen-film than for digital mammography (1.9% and 0.7%, respectively; P < .001). No significant differences were observed in the overall cancer detection rate between the two groups (0.45% and 0.43% in the screen-film and digital mammography groups, respectively; P = .59). The adjusted risk of a false-positive result was higher for screen-film than for digital mammography (odds ratio = 1.32). The adjusted risk was also lower for the digital mammography group when time trends were taken into account. CONCLUSION The lower false-positive risk with use of digital mammography should be taken into account when balancing the risks and benefits of breast cancer screening.

Effect of start age of breast cancer screening mammography on the risk of false-positive results.

OBJECTIVE To estimate the false-positive (FP) risk according to the start age of mammography screening (45-46 or 50-51 years). METHOD Data from eight regions of the Spanish breast cancer screening programme from 1990 to 2006 were included (1,565,364 women). Discrete time-hazard models were used to ascertain the effect of age and time-related, programme-related and personal variables on FP leading to any further procedure and to invasive procedures (FPI). In a subset we estimated the differential FP risk of starting screening at 45-46 years (175,656 women) or 50-51 (251,275). RESULTS A start age of 45-46 versus 50-51 years increased both FP (OR=1.20; 95%CI: 1.13-1.26) and FPI risks (OR=1.43 (95%CI: 1.18-1.73).Other factors increasing FP risk were premenopausal status (FP OR=1.26; 95%CI: 1.23-1.29 and FPI OR=1.22; 95%CI: 1.13-1.31), prior invasive procedures (FP OR=1.52; 95%CI: 1.47-1.57 and FPI (OR=2.08; 95%CI: 1.89-2.28) and family history (FP OR=1.16; 95%CI: 1.12-1.20 and FPI OR=1.26; 95%CI: 1.13-1.41). FP risk was increased by double reading (OR=1.36; 95%CI: 1.23-1.51) and FPI risk by double views (OR=1.34; 95%CI: 1.18-1.52). Both the cumulative FP and FPI risks were higher in women commencing screening at 45-46 years versus 50-51 years (33.30% versus 20.39% and 2.68% versus 1.76%). CONCLUSIONS Starting screening earlier increases the cumulative risk of FP and FPI.

Effect of false-positive results on reattendance at breast cancer screening programmes in Spain.

BACKGROUND Mammography is the only breast screening method, we are aware of today, which is able to reduce mortality from breast cancer. Nevertheless, this procedure carries an inherent risk of false-positive screening mammogram. The association between these results and reattendance at the next scheduled screening mammogram is controversial. The aim of this study was to examine the effect of a false-positive screening mammogram and womens characteristics on reattendance in eight regional population-based breast cancer screening programmes in Spain. METHODS This study included 1 383 032 women aged 44-67 years who were initially screened for breast cancer between 1990 and 2004. To investigate factors associated with reattendance, logistic regression models were used. RESULTS The mean age of women at first screening was 53.6 years (SD = 6.1 years). Of 120 800 women with a false-positive screening mammogram, 78.3% returned for a subsequent screening mammogram compared with 81.9% of those with a negative result (P < 0.001). Multivariate analysis showed that women with a false-positive result at first screening mammogram were less likely to reattend (OR = 0.71; 95% CI 0.70-0.73) and that the likelihood was lower in those who had undergone invasive additional tests (OR = 0.56; 95% CI 0.53-0.59). CONCLUSION A false-positive screening mammogram in the first screening negatively affected attendance at the subsequent screening. The results of this study could be useful to improve the screening process and to increase womens compliance.

Cost-effectiveness of early detection of breast cancer in Catalonia (Spain)

BackgroundBreast cancer (BC) causes more deaths than any other cancer among women in Catalonia. Early detection has contributed to the observed decline in BC mortality. However, there is debate on the optimal screening strategy. We performed an economic evaluation of 20 screening strategies taking into account the cost over time of screening and subsequent medical costs, including diagnostic confirmation, initial treatment, follow-up and advanced care.MethodsWe used a probabilistic model to estimate the effect and costs over time of each scenario. The effect was measured as years of life (YL), quality-adjusted life years (QALY), and lives extended (LE). Costs of screening and treatment were obtained from the Early Detection Program and hospital databases of the IMAS-Hospital del Mar in Barcelona. The incremental cost-effectiveness ratio (ICER) was used to compare the relative costs and outcomes of different scenarios.ResultsStrategies that start at ages 40 or 45 and end at 69 predominate when the effect is measured as YL or QALYs. Biennial strategies 50-69, 45-69 or annual 45-69, 40-69 and 40-74 were selected as cost-effective for both effect measures (YL or QALYs). The ICER increases considerably when moving from biennial to annual scenarios. Moving from no screening to biennial 50-69 years represented an ICER of 4,469€ per QALY.ConclusionsA reduced number of screening strategies have been selected for consideration by researchers, decision makers and policy planners. Mathematical models are useful to assess the impact and costs of BC screening in a specific geographical area.

Geographical variations in the benefit of applying a prioritization system for cataract surgery in different regions of Spain

BackgroundIn Spain, there are substantial variations in the utilization of health resources among regions. Because the need for surgery differs in patients with appropriate surgical indication, introducing a prioritization system might be beneficial. Our objective was to assess geographical variations in the impact of applying a prioritization system in patients on the waiting list for cataract surgery in different regions of Spain by using a discrete-event simulation model.MethodsA discrete-event simulation model to evaluate demand and waiting time for cataract surgery was constructed. The model was reproduced and validated in five regions of Spain and was fed administrative data (population census, surgery rates, waiting list information) and data from research studies (incidence of cataract). The benefit of introducing a prioritization system was contrasted with the usual first-in, first-out (FIFO) discipline. The prioritization system included clinical, functional and social criteria. Priority scores ranged between 0 and 100, with greater values indicating higher priority. The measure of results was the waiting time weighted by the priority score of each patient who had passed through the waiting list. Benefit was calculated as the difference in time weighted by priority score between operating according to waiting time or to priority.ResultsThe mean waiting time for patients undergoing surgery according to the FIFO discipline varied from 1.97 months (95% CI 1.85; 2.09) in the Basque Country to 10.02 months (95% CI 9.91; 10.12) in the Canary Islands. When the prioritization system was applied, the mean waiting time was reduced to a minimum of 0.73 months weighted by priority score (95% CI 0.68; 0.78) in the Basque Country and a maximum of 5.63 months (95% CI 5.57; 5.69) in the Canary Islands. The waiting time weighted by priority score saved by the prioritization system varied from 1.12 months (95% CI 1.07; 1.16) in Andalusia to 2.73 months (95% CI 2.67; 2.80) in Aragon.ConclusionThe prioritization system reduced the impact of the variations found among the regions studied, thus improving equity. Prioritization allocates the available resources within each region more efficiently and reduces the waiting time of patients with greater need. Prioritization was more beneficial than allocating surgery by waiting time alone.

Determining the lifetime density function using a continuous approach

Objective: To apply a continuous hazard function approach to calculate the lifetime density function (LDF) at any age, and to compare the life expectancies derived from the LDF with those obtained with standard life table (SLT) methods. Methods: Age-specific mortality rates were modeled through a continuous hazard function. To construct the cumulative hazard function, appropriate integration limits were considered as continuous random variables. The LDF at any age was defined on the basis of the elemental relationships with the cumulative hazard function. Life expectancies were calculated for a particular set of mortality data using the SLT approach and the expectancy of the LDF defined. Applications and comparisons: The proposed approach was applied using mortality data from the 2001 census of Catalonia (Spain). A Gompertz function was used to model the observed age-specific mortality rates, which fitted the observed data closely. The LDF and the life expectancy, median and standard deviation of the LDF were derived using mathematical software. All differences, in percentages, between the life expectancies obtained from the two methods were 1.1% or less. Conclusions: The LDF gives a wider interpretation of life duration, by extending a deterministic value like life expectancy to a fully informative measure like the LDF.

Unmet needs for cataract surgery in Spain according to indication criteria. Evaluation through a simulation model

Aims: Despite the increase in cataract surgery rates, the volume of unmet needs for this type of surgery in the population is substantial due to ageing and widening of the indication criteria. Our objective was to assess future trends in needs for cataract surgery according to different scenarios of indication criteria. Methods: A discrete-event simulation model was built for the population aged 50 years or older in five regions of Spain (45.7% of the population). Different scenarios of worse eye visual acuity thresholds for indication criteria were compared. Data from the North London Eye Study were used to project the baseline needs for surgery onto the study population. The surgery rate of each region was calculated using the Minimum Data Set. The model used data for the year 2003 and the simulation horizon was 5 years. Results: The volume of need predicted for the year 2008 when scenarios of 0.5 (20/40) and 0.4 (20/50) visual acuity thresholds were used was 69 214 and 51 315 surgeries needed per million inhabitants, respectively. However, unmet needs decreased when a 0.3 (20/70) threshold was used. The increment in the cataract surgery rate needed to prevent the cataract backlog from increasing was 60% for a 0.5 threshold and 50% for a 0.4 threshold. Conclusion: Application of indication criteria following current guidelines would substantially increase unmet needs for surgery in the next 5 years.

Effect of participation on the cumulative risk of false-positive recall in a breast cancer screening programme

One of the major concerns in breast cancer screening programmes is the number of women with mammographic abnormalities requiring further investigation that finally turn out to be negative. It has been reported that, apart from giving rise to anxiety1 and higher costs,2 such false-positivemammogram results might also affect subsequent screening attendance. Several studies have estimated the cumulative risk of falsepositive mammograms during a woman’s lifespan, and all have found a high cumulative false-positive recall rate, ranging from 20% to 50% after 10 rounds of screening. Elmore et al., analysed a cohort of women with irregular programme attendance, while other authors analysed cohorts of women participating in all screening rounds. Comparison of their results is difficult not only because of differences between health systems and protocols, but also due to differences in the selection criteria of the target population to estimate the cumulative risk of false-positive recall. It was hypothesized that estimations which only included women who participated in all screening rounds might be biased since, if false-positive results affect attendance at subsequent screening rounds, this might lead to cumulative false-positive rate underestimation in this cohort. To investigate this issue, the cumulative risk of false-positive recall was estimated for two groups of women with different profiles of adhesion to the programme using a cohort of women participating in a population-based breast cancer screening programme. Furthermore, the association between women’s characteristics and the cumulative risk of false-positive

Impact of the distinct diagnostic criteria used in population-based studies on estimation of the prevalence of knee osteoarthritis

OBJECTIVE To assess the impact of the distinct diagnostic criteria used in population-based studies on estimation of the prevalence of knee osteoarthritis. METHODS We performed a search for population-based studies of the prevalence of knee osteoarthritis carried out in the general noninstitutionalized population in Europe or the USA. RESULTS Eight articles were selected, six from Europe and two from the USA. Depending on the study, definition of knee osteoarthritis was based on symptomatic criteria (pain), radiological criteria (the Kellgren and Lawrence scale) or a combination of both symptomatic and radiological criteria. Prevalence estimates ranged from 2.0 to 42.4% with symptomatic criteria, from 16.3 to 33.0% with radiological criteria, and from 1.5 to 15.9% when both criteria were combined. The prevalence was higher for women and increased with age, with the exception of some prevalences estimated through symptoms, which decreased in ages older than 80 years. CONCLUSIONS There is a lack of consensus on the criteria used to diagnose knee osteoarthritis in population-based studies of prevalence. Consequently, prevalence estimates vary widely, depending on the diagnostic criteria used, and not only by age and sex. The prevalence was higher when radiological evidence alone was used, followed by symptomatic criteria and by combinations of both.