The results of systematic reviews are bound to differ between the studies they include. A systematic review will have some variability, which can be called heterogeneity. It is possible to differentiate between types of heterogeneity. Variability in the participants, interventions and outcomes studied may be described as clinical diversity (sometimes called clinical heterogeneity), and variability in study design and risk of bias may be described as methodological diversity (sometimes called methodological heterogeneity). It is caused by clinical, methodological, or both. The observed interventions effects differ from one another more than would be expected due to chance (random error) alone. This is the convention. We’ll refer to statistical heterogeneity as heterogeneity.

The intervention effect will be affected by patient characteristics, specific interventions, or clinical variation. Clinical variation could lead to heterogeneity. In other words, the true intervention effect will be different in different studies.

Methodological differences, including blinding or concealment of allocation use, can lead to variations in observed intervention effects. Significant statistical heterogeneity in response to methodsical diversity or different outcome assessments could indicate that studies may not be estimating the same number, but it doesn’t necessarily suggest that they are all wrong. A study with heterogeneity solely because of methodological diversity could have bias. However, empirical evidence indicates that design factors can have an effect on clinical trial outcomes. The purpose of a review is to determine whether the studies covered in it are varied. Sometimes reviews will contain studies that answer multiple questions. This is often the case when there are several interventions available to treat the same condition. (See Chapter 5, Section ). It is important to separate out the studies of each intervention and analyse them. A meta-analysis is only appropriate when the group of studies has sufficient homogeneity in terms of intervention, participants and outcomes for a useful summary. Meta-analysis can often be more helpful than one clinical trial. One common example is the fact that systematic reviews combine apples and oranges and can lead to a useless result. The same holds true for apples and lemons that are intrinsically interesting, but it might not be true if used in conjunction with a larger question regarding fruit. By combining the results of trials that evaluated each drug, one can reasonably estimate the average effect for a particular class.

There may be specific interest in a review in investigating how clinical and methodological aspects of studies relate to their results. If possible these studies should be pre-specified, i.e. The systematic review protocol should include these investigations. It is legitimate for a systematic review to focus on examining the relationship between some clinical characteristic(s) of the studies and the size of intervention effect, rather than on obtaining a summary effect estimate across a series of studies (see Section ). Meta-regression may best be used for this purpose, although it is not implemented in Rev. The Man (see Section

Readers don’t necessarily need stories that are too technical. NPR’s NPR story regarding a test to determine if a person has cancerous blood doesn’t mention specificity or sensitivity. It communicates clearly the dangers of false-positive results. The story quotes experts that warn against negative results giving patients “false comfort” while a positive result could lead to “unnecessary and costly medical odysseys.” Our CNN review of a Parkinson’s test also received praises. They praised the story’s provision of sensitivity and specificity values, but noted that readers could have been given more context as to what these statistics mean. According to them, the story should have explained more about how a low-specificity test can cause false-positives (people who aren’t actually suffering from this condition will be told otherwise).

News releases and stories tend to be more accurate in describing tests than they are and minimize potential risks.

This Guardian story touted an experimental blood test that was said not only to “detect autism in children” but also “could lead to earlier diagnosis.” Our reviewers noted that the story, based on a study of just 38 children, offered no data to back up its claim; nor did it warn of the harm that a false-positive or false-negative result could inflict on children and their parents.

This USA Today story on genetic testing for breast cancer was also criticized. Reviews stated the story didn’t contain enough information to help readers make informed choices about 23and, which was approved recently. Do the me test. Is there a way to find out how many false-positive results you get? Or false negatives? How does this translate into breast cancer risk?

Richard Hoffman MD MPH was the Director of Division of General Internal Medicine of the University of Iowa Carver College of Medicine. According to him, accuracy is often defined in medical literature as the total of true positive and false negative results divided by all other test results. (Read the linked post above for more detail on how this is calculated.) The test would be unable to identify any disease-related patients, so even though it is completely useless, the accuracy of the test will still be high. “For example, 10 percent of 100 patients may have this disease. The accuracy of the test based upon the true negatives would therefore be 90%,” he said.

There are many stories that don’t clarify whether or not they use the definitions of accuracy in the medical literature. This can add confusion.

Add the results review above to your cart. You must add the exact number of test panels to your cart.

After receiving the results of your tests via email click the scheduling button.

It’s True. You. Labs.com will contact you to confirm your appointment.

Please read the Disclaimer/TOS. You agree that it will only be an explanation of results and not an interpretation. Please note that any information presented is for education only. The information will not be used to diagnose, heal, cure, prevent, or mitigate any disease. By proceeding with this conversation you understand that all medical history may not be obtained when explaining test results, therefore no doctor/patient relationship is formed. Treatment recommendations can not be given directly. These conversations do not substitute for medical advice. Recordings of calls can be made for quality purposes. Certain tests do not qualify for a review. These exceptions will be clearly displayed on the respective test pages. Be sure to carefully read your order.

This review was not found helpful by 0 people.

The following review was helpful to 1 person:

Below review was found to be helpful by 0 persons:

We split air purifiers into three distinct “sizes”: those designed for small spaces like kids’ bedrooms, dorm rooms, and offices; those for general living spaces such as enclosed living rooms and master bedrooms; and those for large spaces like combined living/cooking/dining spaces or spaces with cathedral ceilings. The categories also broadly correspond to price the larger the space, generally the more expensive the purifier you need to keep the air clean. You should always “oversize” your purifier. It will enable you to use the purifier at a quieter and slower speed while still cleaning the room effectively.

In order to classify purifiers, we use air changes per an hour (or ACH) in hypothetical rooms measuring 150, 350, 500, and 500 feet. This assumes 8-foot ceilings. This measure is used to determine how many purifiers can circulate air in a space in 60 minutes. It also provides an initial baseline for categorizing purifiers and comparing them. A purifier should be able to circulate 4 ACH in order to be considered sufficient for each space. Our eight-year experience in testing has proven that 4 ACH allows for rapid and complete purification of high polluted air. We also know that any lower performance will lead to significantly reduced performance.

Using ACH for air purifier classification solves a common issue in how manufacturers classify their purifiers. It’s simple for potential customers and sellers to give a square-footage rating. But square-footage ratings are essentially meaningless when you’re comparing two rooms with different ceiling heights. Worse, manufacturers calculate their ratings in different ways, often resulting in massively inflated square-footage claims. ACH gives us a complete picture of a machine’s capabilities. It is calculated based on the size and volume of a space.

Noting that 4 ACH minimum refers to the largest volume of air that purifiers can move when it is at its highest setting, it’s important that you remember this. This setting would be used in extreme pollution situations, like when dealing with wildfire smoke. But on their highest setting, most purifiers are too loud above 50 decibels to be tolerable as a background for conversation, sleep, or TV watching. Our picks are able to keep your air fresh in the recommended room size on a quiet, medium setting.

We generally only test purifiers that have HEPA certification. According to North American standards, true HEPA means that purifiers must remove at least 99.97% airborne particles with diameters less than 0.3 microns in one pass. The human hair measures between 20 to 180 microns. The 0.3-micron-diameter is not an exaggerated number. This is because the Association of Home Appliance Manufacturers – a trade group – considers it to be the largest particle that can be eliminated by HEPA type filtration. This article explains the mechanism in more detail. The Blue Pure 311 and Blue Pure 311 are our top picks for medium-sized rooms. Neither Blueair model is true-HEPA rated, but both are certified by AHAM to have clean air delivery rates (CADR) of 350 and 250, respectively, and they performed exceptionally well in our testing, where we measure each purifier’s effectiveness at capturing HEPA-standard 0.3-micron particles. CADR numbers in effect give the cubic feet per minute of perfectly pure air that a purifier can produce on its maximum setting. The CADR tests measure purifier effectiveness on three different pollutants tobacco smoke, dust, and pollen that correspond to particles of 0.09 to 1.0 micron, 0.5 to 3.0 microns, and 5.0 to 11.0 microns, respectively, so in a sense they represent a tougher standard. The HEPA 0.3 micron standard is within the range of the tobacco-smoke tests. Blue Pure 411 models are filtered the same way as the 311 and 211 Auto.

We also evaluate the objective factors above and weigh the purifier’s value, but we don’t set a price limit for each size room. To judge value, we compare specs (especially ACH), estimated upkeep and electricity costs over the course of five years’ operation, our test results, the findings of other independent reviews, ratings from owners, and manufacturers’ histories of reliability and customer service. This will allow us to identify purifiers that have higher upfront costs than their ratings and specifications.

We do not prioritize smart functionality, which generally means receiving more information from and having more control of a purifier via an app. We don’t consider smart functionality a necessity because our years of testing have proven that a good air purifier creates and maintains excellent air quality simply when allowed to run continuously on a moderate setting. While we appreciate having the information you need, it is possible to command the purifier via voice or remotely. A separate guide has been published on air quality monitors. We found that they are the most effective way to understand the effects of purifiers on air quality.

Adam Brown and Jeemin Khon

Six out of 18 meters were not passed by the Diabetes Technology Society’s Blood Glucose Measure Surveillance Program. Is yours among the six that made it?

You want more information like this?

The Diabetes Technology Society (DTS) recently revealed long-awaited results from its Blood Glucose Monitor System (BGMS) Surveillance Program . This rigorous test verified the accuracy of 18 blood glucose meters (BGMs) that are widely used in the US. These FDA-cleared meters had been purchased in retail shops and thoroughly tested at three locations. The results were interpreted by over 1,000 individuals (including 840 persons with diabetes). The results were troubling: only six out of the 18 devices met the DTS passing standard for meter accuracy – within 15% or 15 mg/dl of the laboratory value in over 95% of trials.

Devices that were successful included:

Contour Next (formerly Bayer) from Ascensia – 100% Accu Chek Aviva Plus Roche Roche – 98% Walmart Reli. Arkray, Confirm Micro – 97% CVS Advanced – Agamatrix, 97% and 97% respectively – All for 97%. Style Lite, Abbott – 96% Accu Chek Smart. Roche View: 95%

Walmart Reli. Arkray Prime: 92% Two Touch Verio. Scan Prodigy Auto Code at 92% – 90% one. Touch Ultra 2, from Life. Check out Scan. Ultima from Abbott – 89% Contour Classic Bayer- 89% Embrace Omnis Health- 88% True Test from HDI/Nipro/Trividia – 88% Track from HDI/Nipro/Trividia – 81 Solus V2 From Bio. Sense Medical – 76% Advocate Recode+ from Diabetic Supply of Suncoast – 76 Gmate Smart (Philosys) – 71%. You can find all of this data here. FDA only reviews meters that have been used in company trials. This independent review purchased the meters through retail stores and tested them thoroughly at accredited research centers. It should be noted that the study’s standards for accuracy were even higher than FDA standards.