Dynamic DeepHit: A Deep Learning Approach for Dynamic Survival Analysis With Competing Risks Based on Longitudinal Data - Songwooseok123/Study_Space GitHub Wiki
[๋ ผ๋ฌธ๋งํฌ] (https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8681104)
The first to investigate a deep learning approach for dynamic survival analysis with competing risks on longitudinal data
- Dynamic-DeepHit๋ longitudinal data๋ก๋ถํฐ time-to-event distribution์ ํ์ตํ์ฌ, dynamicํ survival prediction์ ํ ์ ์๋ค.
(dynamic์ด๋ ์๋ก์ด measurement๊ฐ ๋ค์ด์์ ๋ prediction์ด ๊ฐ๋ฅํ๋ค๋ ๋ง์ธ๋ฏ) - ๊ฐ covariate(feature)๊ฐ ๊ฐ event(risk)์ ์ผ๋ง๋ ์ํฅ์ ๋ฏธ์น๋์ง interpretation๋ ๊ฐ๋ฅํ๋ค.
- longitudinal measurements์ temporal importance๋ ์ ์ ์๋ค.
- ์ด๋ค ์ฌ๊ฑด์ ๋ฐ์ ํ๋ฅ ์ ์๊ฐ์ด๋ ๋ณ์์ ํจ๊ป ์๊ฐํ๋ ํต๊ณ ๋ถ์ ๋ฐ ์์ธก ๊ธฐ๋ฒ
-> ๋ฐ์ดํฐ๋ก๋ถํฐ ์์กดํจ์,์ํํจ์๋ฅผ ์ถ์ ํ๊ณ ํด์ํ๋ ๊ฒ
-> ๊ด์ฌ์๋ event์ ๋ฐ์์๊ฐ๊ณผ covariate(feature)์์ ๊ด๊ณ๋ฅผ ์๋ ค์ค ์ ์์. - ex) ์ ๊ท ๊ฐ์
๊ณ ๊ฐ์ด ์๋น์ค๋ฅผ ์ธ์ (time)๊น์ง ์ด์ฉํ ์ง(์์กด),์ธ์ ๊ณ ๊ฐ์ด ์ดํํ ์ง(event = risk) ,์ด๋ค ํ๋(covariate = feature)์ด ๊ณ ๊ฐ ์ ์ง(์์กด)์ ์ํฅ์ ๋ฏธ์น๋์ง ๋ถ์,
- survival function(์์กดํจ์) : ์๊ฐ t ์ดํ์ ์์กดํ ํ๋ฅ
- hazard function(์ํํจ์) : ํน์ ์๊ฐ t์ event๊ฐ ๋ฐ์ํ ํ๋ฅ -> ์๋ฅผ ๋ค์ด event๊ฐ ๊ณ ๊ฐ์ ์ดํ์ผ ๋ ์ํํจ์ ๋ชจ์์ ๋ณด๊ณ ๊ณ ๊ฐ์๊ฒ ์ด๋ฒคํธ๋ ํํ์ ์ ๊ณตํ ํ์ด๋ฐ์ ๊ฒฐ์ ํ ์ ์์.
- Survival analysis(์์กด๋ถ์)with competing risks(event) :
- event๊ฐ ์ฌ๋ฌ๊ฐ์ธ๋ฐ, ๋์์ ์ผ์ด๋์ง๋ ๋ชปํจ. ์๋ฅผ ๋ค์ด ์ฌ๋ง์์ธ.-> categoricalํ ์ปฌ๋ผ์ ๋ชจ๋ ์ด๋ฒคํธ๊ฐ ๋ ์ ์์ ๋ฏ
- CIF(๋์ ์ํํจ์) : t ์์ ์ ๊น์ง ๊ณ ๊ฐ์ด ์ดํํ ํ๋ฅ ์ ๋ชจ๋ ๋ํ ๊ฒ.
- ๋งค๋
๋ฐ์ดํฐ๊ฐ ์ธก์ ๋๋๋ผ๋, ๋ณดํต last available measurement๋ฅผ ๊ธฐ๋ฐ์ผ๋ก ๋ถ์๋จ.
-> it is essential to incorporate longitudinal measurements rather than discarding valuable information recorded over time, this allows us to make better risk assessments on the clinical events.
- still maintain a propotional hazard assumption -> ์๊ฐ๊ณผ ๊ด๊ณ์์ด ์ํํจ์๊ฐ ์ผ์ ํ๋ค๋ ๊ฐ์
- not fully dynamic; survival predictions are only available at the predefined landmarking times, not at times at which new measurements are obtained.
- it makes assumptions about the underlying stochastic process for the survival model, which may not be true in practice -> limiting the model in terms of learning the relationships between the covariates and events of interest.
- only incorporates a subset of the longitudinal history up to the landmarking time, which may result in information loss when making predictions
- provide only static survival analysis: use only current information to perform the survival predictions and most of theworks focus on a single risk rather than multiple risks.
DynamicDeepHit learns, on the basis of the available longitudinal measurements, a data-driven distribution of first hitting times.
-
observed covariates
- static (time-invariant) and time-varying covariates that are recorded for a period of time
- static (time-invariant) and time-varying covariates that are recorded for a period of time
- time-to-event(s) : ๋ถ์ฐ์์ ์ด๊ณ , irregulargํ๊ณ t_max ์ฆ limit์ด ์๋ ๋ฐ์ดํฐ
- a label indicating the type of event (e.g., death or adverse clinical event) including right-censoring.
- probability that a particular event kโ โ K occurs on or before time ฯ โ (conditioned on the history of longitudinal measurements X โ)
- longitudinal measurements have been recorded up to tโ_J
- x ํน์ฑ์ ๊ฐ์ง ์ํ์ด, t์์ ๋ด์ ์ด๋ฒคํธ k๊ฐ ๋ฐ์ํ ํ๋ฅ ์ ๊ตฌํ๋ ๊ฒ
- CIF true๊ฐ ๋ชฐ๋ผ์ ์ถ์ ๊ฐ ์ธ๊ฑฐ์.
- learns, on the basis of the available longitudinal measurements, a data-driven distribution of first hitting times of competing events.
- learns the complex relationships between trajectories and survival probabilities
-
- Competing risks are not independent and must be treated jointly
- handles the history of longitudinal measurements and predicts the next measurements of time-varying covariates
- encodes the information in longitudinal measurements into a fixed-length vector (context vector) using RNN
- We employ a temporal attention mechanism [18] in the hidden states of the RNN structure when constructing the context vector
- access the necessary information, which has progressed along with the trajectory of the past longitudinal measurements, by paying attention to relevant hidden states across different time stamps
- GRU
-
- For each time stamp j = 1,...J โ 1,
the RNN structure takes a tuple of
$(x_j , m_j , ฮด_j )$ as an input and outputs$(y_j , h_j )$ , where y_j is the estimate of time-varying covariates after time$ฮด_j$ has elapsed, i.e.,$x_j+1$ and$h_j$ is the hiddenstate at time stamp j
- to unravel temporal importance of the history of measurements in making risk predictions
- Input : shared Sub-network๋ฅผ ํต๊ณผํ๊ณ ๋์จ context vector์ the last measurements
- ๋์์ด ๋๋ Event์ ๊ฐ์๋งํผ Cause-Specific Sub-network๋ฅผ ๊ตฌ์ฑ(๊ธฐ์กด์ ์์กด๋ถ์ ๋ฐฉ๋ฒ๋ค๊ณผ๋ ๋ฌ๋ฆฌ ์ฌ๋ฌ ์ด๋ฒคํธ์ ๋ํด์ ๋ถ์ํ ์ ์๋ค๋ ์ ์ด DeepHit์ ๊ฐ์ ์ด์์)
- ๊ฐ Event๋ณ Cause-Specific Sub-network๋ฅผ ํต๊ณผ
- estimate the joint distribution of the first hitting time and competing events that is further used for risk predictions.
(= probability of the first hitting time of a specific cause k)
- Event ๋ณ Output Layer ๋ฒกํฐ๋ค์ ๋ชจ๋ ์ด์ด๋ถ์ด๊ณ , Softmax ํจ์๋ฅผ ํต๊ณผ
- ์ด๊ฑธ๋ก CIF ์ถ์ ๊ฐ ๊ตฌํด
- ์ด๋ฒคํธ ๋ฐ์ ์๊ฐ์ ๋ํ Loss ํจ์
- the negative log-likelihood of the joint distribution of the first hitting time and events,
which is necessary to capture the first hitting time in the right-censored data
- (not censored; i๋ฒ์งธ ์ํ์ด ์ด๋ฒคํธ๊ฐ ๋ฐ์ํ ๊ฒฝ์ฐ): captures both the โeventโ & โtimeโ at which the event occurs -> ์ด๋ฒคํธ๊ฐ ๋ฐ์ํ๋ ์๊ฐ์ ์ ๋ง์ถ์๋ก Loss ํจ์๊ฐ ๊ฐ์
- (censored ; i๋ฒ์งธ ์ํ์ด ์ด๋ฒคํธ๊ฐ ๋ฐ์ํ์ง ์์ ๊ฒฝ์ฐ): captures โtimeโ censored -> ์ด๊ฒ์ Censoring ๋ฐ์ดํฐ(์ด๋ฒคํธ ๋ฐ์ ์ฌ๋ถ๋ฅผ ๋ชจ๋ฅด๋ ๋ฐ์ดํฐ)์ ๋ํ์ฌ, ๊ด์ธก ์์ ์ด์ ๊น์ง ์๋ฌด ์ด๋ฒคํธ๋ ๋ฐ์ํ๋ฉด ์๋๊ฒ ํ๋ Loss ํจ์
- ์ด๋ฒคํธ๊ฐ ๋ฐ์ํ ์์ ์ด ๋ค๋ฅธ ๋ ์ํ๋ก๋ถํฐ ์ด๋ฒคํธ ๋ฐ์ ์์๋ฅผ ๋งํ๋ Loss ํจ์
- i๋ฒ ์งธ ์ํ์ด j๋ฒ ์งธ ์ํ๋ณด๋ค ์ด๋ฒคํธ k๊ฐ ๋จผ์ ๋ฐ์ํ์ ๋์ A๋ 1์ ๋ฐํํ๊ณ , ๋ ์ํ์ CIF ์ถ์ ์น์ ์ฐจ์ด๊ฐ ํด์๋ก L2๊ฐ ์์์ง. ์ฆ, ๋ชจ๋ ์ํ ์๋ค์ ์์๋ฅผ ๋งํ๋๋ฐ, CIF ์ถ์ ์น์ ์ฐจ์ด๊ฐ ์ต๋ํ ์ปค์ง๋๋ก Loss ํจ์๊ฐ ์ค๊ณ
- concentrate on discriminating estimated individual risks for each cause
- estimated CIFs calculated at different times
- to fine-tune network to each โcause-specific estimated CIFโ
- penalizes incorrect ordering of pairs
- adapts the idea of concordance
( = patient who dies at s should have higher risk at time s , than a patient who survived longer than s )
- coefficients ฮฑk : chosen to trade off ranking losses of the k-th competing event
- assume here that the coefficients ฮฑk are all equal (i.e. ฮฑk=ฮฑ )
- ฮท(x,y) : convex loss function
- use the loss function ฮท(x,y)=exp(โ(xโy)ฯ. ).
- coefficients ฮฑk : chosen to trade off ranking losses of the k-th competing event
- incorporates the prediction error on trajectories of timevarying covariates to capture the hidden representations of the longitudinal history and to regularize the network.
- UK Cystic Fibrosis Registry
- 5,883 patients
- between ์ฐ๊ฐ 2009-2015.