## How many frailty models are there?

One can distinguish two broad classes of frailty models: (1) models with an univariate survival time as endpoint and (2) models which describe multivariate survival endpoints (e.g; competing risks, recurrence of events in the same individual, occurrence of a disease in relatives).

**What is a joint gamma frailty model?**

Joint frailty model. The time frame for an individual’s repeated event process may depend on other “terminating” events, such as death. Often the recurrence of serious events, such as tumors and opportunistic infections, is associated with an elevated risk of death.

### What is Andersen Gill model?

The Andersen and Gill model The Andersen and Gill (AG) model assumes that the correlation between event times for a person can be explained by past events, which implies that the time increments between events are conditionally uncorrelated, given the covariates.

**What are ties in survival analysis?**

Tied events are simply when two events occur at the exact same recorded time. For example, if a study measures time until remission in months and subjects 1 and 2 both experienced remission at month 2, then their event times are tied.

## What is the Prisma 7 questionnaire?

PRISMA 7 Questionnaire. A seven item questionnaire to identify disability that has been used in earlier frailty studies and is also suitable for postal completion. A score of > 3 is considered to identify frailty. Walking speed (gait speed).

**What are the stages of frailty?**

The five frailty criteria are weight loss, exhaustion, low physical activity, slowness and weakness. The sum score of these five criteria classifies people into one of three frailty stages (or groups): not frail (score 0), pre-frail (score 1–2) and frail (score 3–5).

### What is an acceptable hazard ratio?

So a Hazard Ratio below 1 is good (less hazardous), and the lower it is, the better. The parenthesized part means that the authors have 95% confidence that the true value of this hazard ratio is between 0.17 and 0.22 (or 17% to 22%), but their best guess is that it’s 20%.

**What is recurrent event?**

In biomedical research, recurrent events refer to events of interest experienced repeatedly by a given individual. These events may all be of the same type, or different types.

## What is Efron’s method of tie handling?

EFRON uses the approximate likelihood of Efron (1977). EXACT computes the exact conditional probability under the proportional hazards assumption that all tied event times occur before censored times of the same value or before larger values.

**What is the Efron approximation?**

The Efron (1977, Journal of the American Statistical Association 72, 557-565) approximation performs far better than the other two, particularly with moderate or heavy ties; even with n = 25 in each group, the bias is under 2%, and for sample sizes larger than 50 per group, it is less than 1%.

### What are the 5 frailty syndromes?

These resources are intended to help address the common ‘frailty syndromes’ of falls, immobility, delirium, incontinence and side effects of medication.

**What is a hazard ratio of 1?**

A hazard ratio of one means that there is no difference in survival between the two groups. A hazard ratio of greater than one or less than one means that survival was better in one of the groups.

## How do I analyze multiple failure time data using Stata?

The steps for analyzing multiple failure data in Stata are (1) decide whether the failure events are ordered or unordered, (2) select the proper statistical model for the data, (3) organize the data according to the model selected, and (4) use the proper commands and command options to stset the data and fit the model.

**What is proportional hazard assumption?**

The proportional hazard assumption is that all individuals have the same hazard function, but a unique scaling factor infront. So the shape of the hazard function is the same for all individuals, and only a scalar multiple changes per individual.

### What are the five dimensions of frailty?

Several studies have used Fried’s frailty phenotype (Fried et al., 2001), which defines frailty as the presence of five components: weakness, slowness, exhaustion, low physical activity, and unintentional weight loss.

**What is p value in Kaplan Meier?**

The p-value to which you are referring is result of the log-rank test or possibly the Wilcoxon. This test compares expected to observed failures at each failure time in both treatment and control arms. It is a test of the entire distribution of failure times, not just the median.

## What is frailty model in statistics?

Frailty models for survival data. A frailty model is a random effects model for time variables, where the random effect (the frailty) has a multiplicative effect on the hazard. It can be used for univariate (independent) failure times, i.e. to describe the influence of unobserved covariates in a proportional hazards model. More inte ….

**What is univariate frailty?**

In essence, the proneness” with binary data. The ﬁrst univariate frailty model was suggested by Beard (1959), co nsidering diﬀerent mortality models. The term frailty

### Which distribution is best for frailty effect?

However, the Gamma and Inverse Gaussian distribution are the most common and widely used in literature for determining the frailty effect, which acts multiplicatively on the baseline hazard [27] and [23].

**What are the weaknesses of a frailty method?**

A weakness is that it is very difficult for the modeling routine to know whether a sensible penalty routine has been supplied. Note that use of a frailty term implies a mixed effects model and use of a cluster term implies a GEE approach; these cannot be mixed. The coxme package has superseded this method.