25

Both. Human cells largely exhibit a phenomenon called senescence - they just give up and die after they reach a certain age via a biochemical mechanism called apoptosis. The outer limit of survivability for human cells is generally understood to be in the 100-120 year range. One of the things that makes a cancer cell cancerous is the deactivation of the ...


12

The claim of modern medicine being responsible for longer lifespans is of course a statistical claim, i.e. the average/net effect. Thus your second assertion does not follow logically. Though it is an interesting point. Diseases, both now and in the past, do not have 100% mortality rates. If you followed the ebola outbreak you'd have heard stories of ...


10

The paper itself describes how this is calculated (see the Methods section), but also see this Q&A at Biology.SE talking more broadly about how efficacy has been defined in these vaccine trials: https://biology.stackexchange.com/q/96941/27148 They define efficacy as the fraction of infected in the vaccine compared to placebo categories, normalized for ...


7

There are two broad types of prevalence statistics: point prevalence and period prevalence. In both cases, more details need to be specified in order to fully describe the statistic. Point prevalence is the proportion of people who have a disease at a given point in time. In other words, the total number of people in a given population who have a disease at ...


7

First of all, your numbers are good, but they depend on when one was born, and are higher for younger people: The lifetime risk of cancer increased from 38.5% for men born in 1930 to 53.5% for men born in 1960. For women it increased from 36.7 to 47.5%. Results are robust to different models for projections of cancer rates. Trends in the lifetime risk of ...


6

An individual person does not have a mortality rate: it means the fraction of people out of a group who die over a specific time period. It may seem like your particular chance of dying is that same number, but it's not: the people who die with condition X may be sicker, have a worse case of it, have something else, be older, and so on. Although 80% of ...


6

The formula used for vaccine efficacy is as follows: VE = (ARU - ARV) / ARU (VE: vaccine efficacy, ARU: attack rate in unvaccinated participants, ARV: attack rate in vaccinated participants) This is equivalent to: VE = 1 - RR (RR: Relative risk) The attack rate is simply the number of new cases divided by the total group size. ARV = 39 / 21,314 = 0....


5

Your back-of-the-envelope calculations seem to be off in estimating the extent of viral load reduction in a treated versus untreated person as well as the risk of transmission for unprotected, untreated sex (5% is much higher than any other number I have seen). Obviously the viral load is not zero because then they wouldn't be HIV positive is not ...


4

In the US, 21 CFR 101 provides reference amounts for serving sizes, which are usually followed somewhat closely (I wasn't able to determine if they are required by law) by food manufacturers. In the specific case of rice, the standard serving size is "140 g prepared; 45 g dry" listed in the format "_ cup(s) (_ g)". Usually, the nutritional label on the ...


4

Many well-done newer studies are supporting the theory that quality trumps quantity when it comes to sleep. This excellent article at lifehack.org lists 12 good sources, including “two studies (which) assessed how sleep quality and quantity affected college students’ health and well-being. The studies concluded that sleep quality was a better predictor for ...


4

Insulin Resistance, Body Weight, Obesity, Body Composition, and the Menopausal Transition (ScienceDirect, 2000) Because bone and muscle have greater density than water, a person with a larger percentage of fat-free mass will weigh more in the water. Conversely, a larger amount of fat mass will make the body lighter in the water. The density of: ...


4

I haven't seen any evidence that the actual death rate has changed at all. See this Q&A: Does COVID-19 have a case fatality rate of 41%? Is this formula correct? The ratio of "deaths/(recoveries+deaths)" does not describe the actual case fatality rate Early in the pandemic, when there are lots of new people infected, almost all of the cases were ...


4

From the CDC (bold added by me): Provisional estimates by causes of death are subject to some nonrandom sampling error. This is because the delay in receiving the report of a death depends on the cause of death. The quarterly provisional estimates are based on data that is more incomplete for the most recent months. Causes of death with more delayed ...


3

In many cases they do reflect the actual diagnosis. It depends on the disease in question. eMerge network work on validation is for example here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3715338. In that study, they used ICD-based definitions but also other available data. Similar work in diabetes mellitus diagnosis is also published (https://www.ncbi....


3

From this answer on Biology.SE (given and researched by me): Yes, this is possible through something called heteropaternal superfecundation (see below for further explanation). Of all twin births, 30% are identical and 70% are non-identical (fraternal) twins. Identical twins result when a zygote (one egg, or ovum, fertilized by one sperm) splits at an ...


3

Short answer: maybe a few, but not instantly. Nicotine poisoning exists but rarely is it fatal. Especially, when it is delivered through smoking. There have been very few incidents of death by nicotine poisoning reported. References: https://en.wikipedia.org/wiki/Nicotine_poisoning http://www.sciencedirect.com/science/article/pii/S0379073809004459 http://...


3

In statistics, the "residual" is what is left over after accounting for the other predictors. I'd suggest that residual is being used here in a similar way. When you classify causes of death, some are easy to put into groups which can also be then sub-categorized (e.g., accidents / transport). In a large population, there will be many deaths that can't be ...


3

Precisely because developed countries have better air quality, nutrition, sanitation, healthcare, etc. life expectancy is higher and cancer is more likely in these countries. This is because cancer is caused by mutations in DNA which accumulate over time. Since life expectancy in general is higher in developed countries, there is more time for mutations to ...


3

There is no standard for calculating "food volumes". The nutrition data of all foods is only consistent by weight. Standardized nutrition data labels all give nutrients per 100 g, frequently also adding the nutrient amount calculated for other weights, for example for one unit of packaging, or one piece when the food is in discrete pieces. When somebody is ...


3

Yes, these are referring to statistical power. Statistical power is the probability of correctly rejecting a null hypothesis given a certain sample size and expected magnitude of effect (i.e., defining the alternative hypothesis). It should be calculated prior to doing a study. Although it is technically possible to calculate post-hoc power (using an ...


3

What you are basically asking for is a called a "power analysis" in statistics. If all you have are proportion data (i.e., 99% vs 98% surviving), then for a two-sided test of the null hypothesis that Group M and Group P have the same survival rate, with an alpha of 0.05, and expected probabilities as you've stated them, you would need at least 2254 subjects ...


3

I think the closest thing to a "standardization of drugs" are the pharmacopeia: USP European Pharmacopoeia Japanese Pharmacopoeia (just some examples) As you will notice, these are not global standards, but each one defines the parameters by which a drug is of adequate quality and purity to be deemed that drug. To generate a global standard, it would be ...


3

Seasonal and cyclical effects have been studied prior to COVID-19, including day-of-week influences on Emergency Department visit volume. For example, in a study of emergency departments in Western New York: “The final ARMA (2,0) model indicated an autoregressive structure with up to a 2-day lag. ED volume is lower on weekends than on weekdays, and ...


3

I haven't seen a lot of research on these intra-weekly (reporting) trends on anything health-related, but there is one paper on such trend on ILI reporting, alas just in the military: In this report, we describe and analyze a periodic pattern in influenza-like illness within active military populations, derived from the Defense Medical Surveillance System ...


3

While hospitals, clinics, long term care homes and such are of course open and working seven days a week, administrative staff typically only work 5 days a week. So someone comes to work Monday and reports 3 deaths (that may actually have occurred on Saturday or Sunday.) They may not do that first thing Monday, they may have other things going on. ...


3

While people don't usually have a preference for dying on particular days determining how they died is subjected to delays. A medical examiner or other expert had to determine whether the death is from covid-19 or one of the many comorbid conditions that the person suffered from. Furthermore, there are deaths in the community that need to be examined. You ...


3

The best data source for looking at total deaths in the COVID-19 era is to look at the CDC's excess deaths data. These data compare actual death data (blue) to seasonal trends (yellow), and indicates weeks for which deaths are greater than would be seasonally expected: You'll note some peaks above expected associated with a worse than average influenza year ...


3

The definition for "exposed" the CDC is using that is referred to in the article you link is "close contact with an infected person (that is, be within six feet for 15 or more minutes)". This is a standard used in contact tracing, where once you identify someone who is infected you go back and try to identify people they had contact with ...


3

San Marino is, from an epidemiology perspective, effectively a city in Italy. It's also quite small (just over 30,000 people), and the total number of deaths there from your source is 80. This is a tiny sample compared to the other countries on that list. Italy is also quite high on that list. ~175 deaths vs ~237 deaths per 100,000 is certainly in the same ...


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