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X Demographics
Mendeley readers
Attention Score in Context
| Title |
New methods for estimating follow-up rates in cohort studies
|
|---|---|
| Published in |
BMC Medical Research Methodology, December 2017
|
| DOI | 10.1186/s12874-017-0436-z |
| Pubmed ID | |
| Authors |
Xiaonan Xue, Ilir Agalliu, Mimi Y. Kim, Tao Wang, Juan Lin, Reza Ghavamian, Howard D. Strickler |
| Abstract |
The follow-up rate, a standard index of the completeness of follow-up, is important for assessing the validity of a cohort study. A common method for estimating the follow-up rate, the "Percentage Method", defined as the fraction of all enrollees who developed the event of interest or had complete follow-up, can severely underestimate the degree of follow-up. Alternatively, the median follow-up time does not indicate the completeness of follow-up, and the reverse Kaplan-Meier based method and Clark's Completeness Index (CCI) also have limitations. We propose a new definition for the follow-up rate, the Person-Time Follow-up Rate (PTFR), which is the observed person-time divided by total person-time assuming no dropouts. The PTFR cannot be calculated directly since the event times for dropouts are not observed. Therefore, two estimation methods are proposed: a formal person-time method (FPT) in which the expected total follow-up time is calculated using the event rate estimated from the observed data, and a simplified person-time method (SPT) that avoids estimation of the event rate by assigning full follow-up time to all events. Simulations were conducted to measure the accuracy of each method, and each method was applied to a prostate cancer recurrence study dataset. Simulation results showed that the FPT has the highest accuracy overall. In most situations, the computationally simpler SPT and CCI methods are only slightly biased. When applied to a retrospective cohort study of cancer recurrence, the FPT, CCI and SPT showed substantially greater 5-year follow-up than the Percentage Method (92%, 92% and 93% vs 68%). The Person-time methods correct a systematic error in the standard Percentage Method for calculating follow-up rates. The easy to use SPT and CCI methods can be used in tandem to obtain an accurate and tight interval for PTFR. However, the FPT is recommended when event rates and dropout rates are high. |
X Demographics
The data shown below were collected from the profiles of 3 X users who shared this research output. Click here to find out more about how the information was compiled.
Geographical breakdown
| Country | Count | As % |
|---|---|---|
| Japan | 1 | 33% |
| Venezuela, Bolivarian Republic of | 1 | 33% |
| Unknown | 1 | 33% |
Demographic breakdown
| Type | Count | As % |
|---|---|---|
| Members of the public | 2 | 67% |
| Scientists | 1 | 33% |
Mendeley readers
The data shown below were compiled from readership statistics for 86 Mendeley readers of this research output. Click here to see the associated Mendeley record.
Geographical breakdown
| Country | Count | As % |
|---|---|---|
| Unknown | 86 | 100% |
Demographic breakdown
| Readers by professional status | Count | As % |
|---|---|---|
| Student > Master | 12 | 14% |
| Researcher | 10 | 12% |
| Student > Doctoral Student | 9 | 10% |
| Other | 8 | 9% |
| Student > Bachelor | 7 | 8% |
| Other | 18 | 21% |
| Unknown | 22 | 26% |
| Readers by discipline | Count | As % |
|---|---|---|
| Medicine and Dentistry | 26 | 30% |
| Nursing and Health Professions | 8 | 9% |
| Agricultural and Biological Sciences | 3 | 3% |
| Biochemistry, Genetics and Molecular Biology | 3 | 3% |
| Social Sciences | 3 | 3% |
| Other | 14 | 16% |
| Unknown | 29 | 34% |
Attention Score in Context
This research output has an Altmetric Attention Score of 2. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 09 July 2021.
All research outputs
#13,574,541
of 23,009,818 outputs
Outputs from BMC Medical Research Methodology
#1,296
of 2,029 outputs
Outputs of similar age
#215,957
of 437,935 outputs
Outputs of similar age from BMC Medical Research Methodology
#24
of 42 outputs
Altmetric has tracked 23,009,818 research outputs across all sources so far. This one is in the 39th percentile – i.e., 39% of other outputs scored the same or lower than it.
So far Altmetric has tracked 2,029 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 10.2. This one is in the 33rd percentile – i.e., 33% of its peers scored the same or lower than it.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 437,935 tracked outputs that were published within six weeks on either side of this one in any source. This one is in the 48th percentile – i.e., 48% of its contemporaries scored the same or lower than it.
We're also able to compare this research output to 42 others from the same source and published within six weeks on either side of this one. This one is in the 42nd percentile – i.e., 42% of its contemporaries scored the same or lower than it.