amastyleinsider

June 18, 2012

Bucking the “Trend” and Approaching “Approaching Significance”

Filed under: statistics — amastyleinsider @ 1:00 pm
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I believe we are on an irreversible trend toward more freedom and democracy – but that could change.

—Dan Quayle

In general usage, the concept of trend implies movement. Not only is this implied in its definitions, but the word can be traced to its Middle High German root of trendel, which is a disk or spinning top.1

In scientific writing, when is a trend not a trend? When it is not referring to comparisons of findings across an ordered series of categories or across periods of time. However, this and related terms are often misused in manuscripts and articles.

Most studies are constructed as hypothesis testing. Because an individual study only provides a point estimate of the truth, the researchers must determine before conducting the study an acceptable cutoff for the probability that a finding of an association is due to chance (the α value, most commonly but not universally set at .05 in clinical studies). This creates a dichotomous situation in interpreting the result: the study either does or does not meet this criterion. If the criterion is met, the finding is described as “statistically significant”; if it is not met, the finding is described as “not statistically significant.”

There are many limitations to this approach. Where the α level is set is arbitrary; therefore, in general all findings should be expressed as the study’s point estimate and confidence interval, rather than just the study estimate and the P value. Despite the limitations, if a researcher designs a study on the basis of hypothesis testing, it is not appropriate to change the rules after the results are available, and the results should be interpreted accordingly. The entire study design (such as calculation of the sample size and study power – the ability of a study to detect an actual difference or effect, if one truly exists) is dependent on setting the rules in advance and adhering to them.

If a study does not meet the significance criterion (for example, if the α level was set as < .05, and the P value for the finding was .08), authors sometimes describe the findings as “trending toward significance,” “having a trend toward significance,” “approaching significance,” “borderline significant,” or “nearly significant.” None of these terms is correct. Results do not trend toward significant—they either are or are not statistically significant based on the prespecified study assumptions. Similarly, the results do not include any movement and so cannot “approach” significance; and because of the dichotomous definition, “nearly significant” is no more meaningful than “nearly pregnant.”

When a finding does not meet statistical significance, there are generally 2 possible explanations: (1) There is no real association. (2) There might be an association, but the study was underpowered to detect it, usually because there were not enough participants or outcome events. A finding that does not meet statistical significance may still be clinically important and warrant further consideration.

However, when authors use terms such as trend or approaching significance, they are hedging the interpretation. In effect, they are treating the findings as if the association were statistically significant, or as if it might have been if the study had just gone a little differently. This is not justified. (Lang and Secic2 make the fascinating observation that “Curiously, P values never seem to ‘trend’ away from significance.”)

A proper use of the term trend refers to the results of one of the specific statistical tests for trend, the purpose of which is to estimate the likelihood that differences across 3 or more groups move (increase or decrease) in a meaningful direction more than would be expected by chance. For example, if a population of persons is ranked by evenly divided quintiles based on serum cholesterol level (from lowest to highest), and the risk of subsequent myocardial infarction is measured in each group, the researcher may want to determine whether risk increases in a linear way across the groups. Statistical tests that might be used for analyzing trends include the χ2 test for trend and the Cochran-Armitage test.

Similarly, a researcher may want to test for a directional movement in the values of data over time, such as a month-to-month decrease in prescriptions of a medication following publication of an article describing major adverse effects. A number of analytic approaches can be used for this, including time series and other regression models.

Instead of using these terms, the options are:

1. Delete the reported finding if it is not clinically important or a primary outcome. OR

2. Report the finding with its P value. Describe the result as “not statistically significant,” or “a statistically nonsignificant reduction/increase,” and provide the confidence interval so that the reader can judge whether insufficient power is a likely reason for the lack of statistical significance.

If the finding is considered clinically important, authors should discuss why they believe the results did not achieve statistical significance and provide support for this argument (for example, explaining how the study was underpowered). However, this type of discussion is an interpretation of the finding and should take place in the “Discussion” (or “Comment”) section, not in the “Results” section.

Bottom line:

1. The term trend should only be used when reporting the results of statistical tests for trend.

2. Other uses of trend or approaching significance should be removed and replaced with a simple statement of the findings and the phrase not statistically significant (or the equivalent). Confidence intervals, along with point estimates, should be provided whenever possible.—Robert M. Golub, MD

1. Mish FC, ed in chief. Merriam-Webster’s Collegiate Dictionary. 11th ed. Springfield, MA: Merriam-Webster Inc; 2003.

2. Lang TA, Secic M. How to Report Statistics in Medicine: Annotated Guidelines for Authors, Editors, and Publishers. 2nd ed. Philadelphia, PA: American College of Physicans; 2006:56, 58.

 

September 15, 2011

Jarring Jargon

Theodore M. Bernstein, in The Careful Writer: A Modern Guide to English Usage, describes jargon as “meaningless, unintelligible speech,” which is how some people might describe their last conversation with their physician. In science and medicine, many barriers to clear communication exist, with jargon being one of them. In fact, it’s so difficult for physicians and patients to communicate clearly that a federal program has been created to promote simplified health-related language nationwide. The Health Literacy Action Plan is a “national action plan to improve health literacy.” The entire action plan is 73 pages (which is probably their first mistake) and it highlights the fact that we have a problem.

As editors, we know that jargon is to be avoided in medical literature. While jargon may evolve for the most innocuous of reasons, it is a vocabulary specific to a profession that sometimes is esoteric or pretentious and that can be confusing to those not familiar with it (sometimes to those familiar with it as well). “Inside talk” can be just that by design—it keeps outsiders out. Therein lies the source of the negative feelings about jargon.

In addition to being exclusive, some jargon is offensive and unprofessional. Have you ever seen an FLK? Probably. That’d be a funny-looking kid. “We bagged her in the ER” sounds ominous; what it means is that a patient was given ventilatory assistance with a bag-valve-mask prior to intubation in the emergency department. Hopefully the emergency department physician didn’t describe the patient as a GOMER. This means “get out of my emergency room” and could refer to, for instance, an elderly patient who is demented or unconscious and near death and who perhaps should die peacefully rather than occupy emergency department resources. In this example, jargon diminishes the complexity of a situation that should be dealt with in a more thoughtful way. As Bernstein writes, “All the words that describe the kinds of specialized language that fall within this classification [of inside talk] have connotations that range from faintly to strongly disparaging.”

Jargon also sometimes violates rules of grammar, eg, turning nouns into verbs, “The doctor scoped the patient,” or creating back-formations, like “The patient’s extremities were cyanosed,” instead of “The patient’s extremities showed signs of cyanosis.” Jargon can sometimes appear to depersonalize, by defining a person in terms of a disease. A “bypassed patient” may be one who has undergone coronary artery bypass graft surgery rather than one who has been overlooked. Sometimes, patients might be referred to by their organs, such as “the lung in room 502” instead of “the patient in room 502 with lung disease.”

The AMA Manual of Style lists examples of jargon to avoid in section 11.4, Jargon. Some other examples that we’ve collected over the years are listed here:

* Collodion baby is better phrased as collodion baby phenotype or “the infant had a collodion membrane at birth.”

* Surgeons perform operations or surgical procedures, not surgeries.

* Rather than say a patient has a complaint, describe the patient’s primary concern.

* Do not use shorthand (eg, exam for examination, preemie for premature infant, prepped for prepared).

* Euphemisms sometimes are not clear and should be avoided: “The patient died” is preferred to “The patient succumbed or expired”; the same holds true for killed vs sacrificed (in discussion of animal subjects).

* Patients aren’t “put on” medication, they’re treated with medication. Also, patients aren’t “placed on” ventilators, they’re given ventilatory assistance.

Certainly jargon does have its place. It is specialized, and those in the same field can use it to communicate precisely and quickly. However, when it comes to medical and scientific publications, jargon is best avoided. Bernstein ends his entry on “inside talk” with the following: “It must never be forgotten that the function of writing is communication.” Clear enough.—Lauren Fischer

August 5, 2011

Ventilate or Ventilation

Filed under: usage — amastyleinsider @ 12:32 pm
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“The patient was ventilated.”

“We decided to ventilate the patient.”

Such statements are commonly overheard in critical care units and other areas when clinicians discuss the care of a patient experiencing insufficient or absent respiration. Both statements use forms of ventilate in ways that—because they appear in this sense in the latest edition of Merriam-Webster’s Collegiate Dictionary—are correct and so may be used in medical journals. However, writers and editors have a valuable opportunity to ensure the continuing precision of the language through careful use of such terms and their variants, referred to as back-formations.

As discussed in the 10th edition of the AMA Manual of Style, “Back-formation is the creation of a new word in the mistaken belief that is was the source of an existing word” (see §11.3, Back-formations, in the AMA Manual of Style, p 407 in print). Back-formations are formed by the removal of a suffix (either a derivational suffix such as -ion or an inflectional suffix such as the plural -s) from a word that actually appeared first, changing its part of speech and forming a new word. Thus, the verb ventilate when used in the clinical sense may well be such a form, as suggested by its appearance in common use slightly later than the appearance of the noun ventilation (early 1900s vs 1890s, respectively).1 Interestingly, however, users of the English language had been busily back-forming for some time before that: ventilate as used in the closely related sense of exposing the blood to air, now obsolete or nearly so apart from its use in the study of physiology, likely also represents a back-formation that appeared some 50 years after ventilation as used in this sense (1660s vs early 1600s, respectively).2

Back-formation plays a valuable role in language evolution, producing neologisms that often subsequently enter common use. However, coining verbs through back-formation can result in medical jargon (see §11.4, Jargon, in the AMA Manual of Style, pp 408-409 in print) that is vague, depersonalizing, and sometimes downright comical in the images it can evoke. Taking the case in point, for example, what does “the patient was ventilated” mean, exactly? Was the patient perforated? Fitted with louvers? Left outdoors?

While it is commonly understood that the use of ventilated in this sense in spoken English denotes the use of a mechanical ventilator or other means of artificial respiratory assistance (eg, use of a bag-valve-mask apparatus), it typically refers to the former. However, in written materials, the use of mechanical ventilation should be explicitly reported when appropriate. In addition, eschewing the use of assistance altogether is perhaps advisable, and certain constructions (eg, “was” or “on” constructions) should be avoided if they lead to ambiguity such as that noted above. For example, “the patient was ventilated” and “the patient was placed on a mechanical ventilator” should be rewritten to read “the patient underwent mechanical ventilation.” In some instances, it might also be helpful to report additional information to clarify whether the intervention was invasive (ie, required endotracheal intubation, nasotracheal intubation, or tracheostomy) or nonvasive (eg, used a mechanical, sealed-mask approach such as BPAP [bilevel positive airway pressure]).

Writers and editors of medical information, then, should be vigilant when using terms coined through back-formation. Such terms should not be used if they do not appear in a current dictionary of reference. Those that do—eg, ventilated—may be used, but writers and editors should take care to ensure that they are not used in ways that are vague, depersonalizing, or unintentionally comical. Ultimately, however, a bit of back-formation is not a bad thing—for example, edit is a back-formation coined from editor.3Phil Sefton, ELS

1. Ventilate. The Compact Oxford English Dictionary. 2nd ed. Oxford, England: Oxford University Press; 1991:2223.
2. Ventilation. The Compact Oxford English Dictionary. 2nd ed. Oxford, England: Oxford University Press; 1991:2223.
3. Back-formation. In: Hoad TF, ed. The Concise Oxford Dictionary of English Etymology. Encyclopedia.com Web site. http://www.encyclopedia.com. Accessed August 5, 2011.

July 27, 2011

Abbreviation Nation

Filed under: abbreviations,editing process,usage — amastyleinsider @ 11:28 am
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Of the reference books I use while editing the Archives journals, my favorite by far is MEDical ABBREViations: 28,000 Conveniences at the Expense of Communication and Safety, 13th Edition, by Neil M. Davis. Not only does it have the most wonderfully snarky title I’ve ever seen on a reference book, but it is the Great Decoder, the book that allows me to make sense of the myriad abbreviations I run across in my daily work.

As much as we are a nation of people who speak largely in cliches and mixed metaphors (I will save my rant about the overused and incorrect “magic bullet” for another day), we are a nation of overabbreviators. The number of organizations that are known by their abbreviation are too many to quantify (NFL, AMA, NORAD). We put out APBs, send out CVs, take our OTC meds, surf our Macs and PCs, and occasionally go AWOL. But when you think about it, do these mean anything? A National Football League is a thing. An NFL is not. What about an AC? Is it an air conditioner? An alternating current? Atlantic City? Though sometimes context can tell us what an abbreviation means, just as often it cannot, and it’s my job to sort these out.

As someone who previously tried to argue that texting is a valid and efficient method of communicating, it may seem hypocritical for me to do a mental fist pump every time I read Mr Davis’ snappy title, but I do. It’s because for every abbreviation that I find easily in my AMA Manual of Style or my MED ABBREV, there are so many that I must ask authors about. This worries me, because I don’t think authors would put these in their articles if they weren’t  routinely used. And though they and their colleagues and most of the American medical community may know exactly what they mean, will readers in Zimbabwe, Thailand, or Argentina? Those readers may have their own set of metaphors, jargon, and abbreviations that makes perfect sense to them. Or they may be students who don’t come across them every day. What happens when we let them slide, or when a journal doesn’t have finicky, know-it-all editors to question them? I worry that it will make journals less accessible, and that it will make medical discourse less accessible. I hate the idea of a medical student somewhere in the world not being able to use one of our articles in his research because I didn’t feel like finding out what something means. And believe me, sometimes I don’t feel like it. But I know I must be persistent, as annoying as it feels to harass a busy professional about something that seems so trivial. And that medical student out there better appreciate it.—Roya Khatiblou, MA

June 21, 2011

Criterion Standard

Filed under: usage — amastyleinsider @ 12:57 pm
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The expression criterion standard, according to the AMA Manual of Style, represents the “diagnostic standard for a particular disease or condition, used as a basis of comparison for other (usually noninvasive) tests. Ideally, the sensitivity and specificity of the criterion standard for the disease should be 100%.” This definition on its face seems a fairly straightforward way to identify the best method for making a diagnosis or the best treatment plan for a given disease.

A controversy, however, emerges in a parenthetical phrase that suggests the alternate expression gold standard be avoided because it “is considered jargon by some.” This assertion is supported by a reference to A Dictionary of Epidemiology, third edition, by John M. Last, published in 1995. Treating it as slang, his entry not only presents gold standard in quotes but, to be sure the reader understands his meaning, follows it with the word “jargon” in parentheses before defining it. Last provides no alternate expression and does not include criterion standard in his dictionary. He does, however, include criterion, which he defines as “[a] principle or standard by which something is judged. See also STANDARD.” And that is defined as “[s]omething that serves as a basis for comparison.”

In his fourth edition, however, Last does not include a gold standard entry. His definitions for both criterion and standard remain the same, and because they have nearly identical definitions could account for his not including an entry for criterion standard.

The gold standard entry returns in the fifth edition, edited by Miquel Porta. It is again presented in quotes but omits the parenthetical naming of it as jargon and defines it as “[a] method, procedure, or measurement that is widely accepted as being the best available. Often used to compare with new methods of unknown effectiveness (e.g., a potential new diagnostic test is assessed against the best available diagnostic test).”

Looking at another source, Annals of Internal Medicine Editor Hal Sox in his book Medical Decision Making never mentions the expression criterion standard. He does, however, talk about gold standard, which he takes out of the realm of epidemiology and into clinical practice by defining the gold standard test as “[t]he procedure that is used to define the true state of the patient.”

Although the “when” of its adoption as the preferred expression for JAMA and the Archives Journals seems to have escaped memory, the “why” remains among most of the medical editors. Some suggest avoidance of gold standard because it crosses disciplines from economics to medicine. As an economic term, it had served as the basic support of paper money. Another consideration, offered by former JAMA Deputy Editor Richard Glass, is that “gold standard …implies more of a sense of permanence than is appropriate for scientific topics.” With new knowledge, he reasons, comes new standards.

Practice, however, defies style preference. A search of JAMA articles in 1998 shows that criterion standard was used 7 times while gold standard was used 42 times. Jumping ahead 10 years, the trend holds: criterion standard was used 9 times; gold standard, 35 times.

Yet the practice of using gold standard over the style recommendation may all boil down to what JAMA Deputy Editor Drummond Rennie wrote in an e-mail. “If we are prepared to consider using ‘criterion standard,’ we should really prefer ‘criterion criterion’ (though ‘standard standard’ sounds a tad less pompous, even if just as meaningless). We all know what ‘gold standard’ means. It has the merit of being customary, memorable, understandable.”

And isn’t that the job of editors? — Beverly Stewart, MSJ

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