Monday, September 30, 2013

How to Read an Article about Harm

Consider this question: how would you test the idea that smoking causes cancer? The best way to do so would be to develop a clinical trial in which half of the participants were required to smoke three packs of cigarettes per day for five years while the other half did not smoke at all. You could then see if there were differences in the rate of lung cancer between the two groups. But, of course, this is not ethical.

Given that we cannot use clinical trials to answer such questions, we can use other designs, including both a case-control study design and a cohort design.  In a case-control study we would look in the past medical records and exposures of cases (those with lung cancer) and controls (those without), and would find that some in each group were heavy smokers while others were not. We could then calculate the difference in rates of cancer between the two groups. In such case, we would end up with an odds ratio; that is, the odds that exposure to smoking leads to lung cancer. In a cohort study, we would follow people forward in time while allowing them to live their life. None have cancer at the beginning of the study. We would find, years down the road, that some in both groups were heavy smokers while others were not, and again we could calculate the difference in rates of cancer between the two groups. In this case, we would end up with a risk ratio.
Risk is associated with disease incidence; that is, the rate of newly diagnosed conditions in a population. In a case-control study, we are starting with people who already have the condition of interest; therefore, we cannot calculate risk (which requires us to newly diagnose a disease), and instead we look at odds.

When we read an article about harm, we need to understand the specific study design being used. While clinical trials are best, they often cannot be conducted. Cohort studies are stronger than case-control studies, since they allow us to calculate the true disease rate in a group. But in studies of harm, other questions to look at while reading are to ensure that the exposures and outcomes in both groups were measured the same way, that follow-up was long enough, that the exposure precedes the adverse outcome, and that the association between exposure and outcome is strong.
It is important to understand that risk and odds ratios do not tell you how frequently a problem occurs, only that the effect occurs more or less often in the exposed group compared to the unexposed group. This can then tell you whether or not to recommend the patient stop the exposure. Once we know, for example, that smoking is associated with a higher rate of cancer, we can advise patients to stop smoking.

For additional information on harm, please see

Monday, September 23, 2013

It’s a New (Publishing) World Out There

In my younger days as a faculty member at National College of Chiropractic (later National University of Health Sciences) I was involved in developing and publishing textbooks. This was a labor of love, since I knew that the potential pay-off likely would never make up for the time I put into working on each book. And indeed, the fist book I published, Fundamentals of Chiropractic Diagnosis and Management, took nearly 4 years to complete, from conception to final publication. Over the course of my career I was involved with 16 books. But as all of us are well aware, we lived in a radically different world than the one I was lived in back in the day.

Our students do not purchase textbooks like we older folk did. I love books, and I actually loved my old chiropractic texts, and each term I was happy to put out the money to buy them. But with so many information sources now available on line, the textbook market has changed in some highly interesting ways. Here is but one example:
Jones and Bartlett, one of many publishing companies, now offers customized course materials. If you use Jones and Bartlett texts for your course, they will provide you the means to build a custom packet of information for your students, drawn directly from the text. When you are done developing the text, which is easy to do online, it will generate either a print or eBook edition.  Put another way, you can take chapters from existing Jones and Bartlett textbooks, select only the ones you wish to use, put them in the order you wish to have your students read them, add in some of your own material, develop your own cover for the book, and then make either the print of eBook copy. You can immediately see the benefit. Your students do not have to buy several textbooks because you need them to read one or two chapters in each; you can just take those chapters and put them in your course book. Instructions for doing so, and a short video clip about this system, can be found at the URL I listed above.

We are seeing this kind of publishing more and more.  Consider the old model, which I admit to using in my own course. I assign a required text, in my case Haneline’s Evidence-Based Chiropractic Practice. I lecture each week using PowerPoint slides drawn from each week’s assigned reading. My guess is that few students actually acquire the text, and likely never read the supporting assigned material. They miss the richness of understanding that reading will bring to the material presented in class. Call me old school, but I always read every assignment I was given. Imagine now being able to use only the chapters you want students to have, at a price reduced from purchasing full textbooks, and even available for their tablet of smart phone? How cool is that?
Jones and Bartlett is hardly the only publisher looking at new models for publication. Elsevier allows you to develop a book containing all the articles you have ever published in Elsevier journals, as but one example. This is not just a vanity project, but if you assign those articles to a class, imagine how nice to have them all in one location, at reasonable cost.

And there is iBookAuthor, and other models that we have been exposed to. Exciting stuff; new horizons for us to conquer.

Monday, September 16, 2013

Clinical Prediction Rules

One of the most important parts of a chiropractor’s daily work with patients is the need to establish a proper and correct diagnosis. Diagnosis is key to the requisite decisions for appropriate care than then follow. As teach students, we generally use heuristic models, where the thinking is linear and directly correlated. That is, students are taught that if a given orthopedic test is positive, it has a specific meaning; if McMurray’s test is positive it means that there is a torn meniscus, for example. As we gather information from an examination, we combine it with our clinical experience and knowledge to close in on what feel is the correct diagnosis. It is for this reason that at Palmer we have focused on training our students to understand the importance of sensitivity and specificity of diagnostic tests, and to derive likelihood ratios from that information.

But this is imperfect at best. Clinical prediction rules (CPR) are designed to try to enhance the accuracy of a clinician’s diagnostic decisions- and the treatment decisions that follow. A clinical prediction rule is defined as “a clinical too that quantifies the individuals contributions that various components of the medical history, physical examination, and basic laboratory results make toward the diagnosis, prognosis, or likely response to treatment in an individual patient.” (1) CPRs are useful in situations where the decision making is complicated and complex.
CPRs a redeveloped using a 3-step process. The first step involves the actual creation or derivation of the rule. Step 2 involves the testing or validation of that new rule, and the final step assesses the impact the rule has had on actual clinical behavior; that is, does it end up making a difference in practice? In order to derive a new rule, it is necessary to locate and identify the factors that might have predictive power. This information could be drawn from the history, physical examination or from lab or other testing. We could then look at a series of patients to see if any of our proposed predictors are present in a large percentage of those patients. Consider, for example, a positive straight leg raise test in patients with prolapsed lumbar discs. To validate a CPR, we need to demonstrate that if we repeatedly apply it with our patients, it leads to the same results (either diagnostically or prognostically). So, in effect, we are now testing the rule in a larger and new population of patients. In the testing process and the research that is done, one can generate either likelihood ratios or odds or risk ratios. These are concepts we are now well aware of.
Here are a couple of relevant CPR papers:
  • Schenk R, Dionne C, Simon C, Johnson R. Effectiveness of mechanical diagnosis and therapy in patients with back pain who meet a clinical prediction rule for spinal manipulation. J Man Manip Ther 2012;20:43-49
  • Stolze LR, Allison SC, Childs JD. Derivation of a preliminary clinical prediction rule for identifying a subgroup of patients with low back pain likely to benefit from Pilates-based exercise. J Orthop Sports Phys Ther 2012;42:425-436

1.       McGinn T, Wyer P, Wisnivensky J, et al. Clinical prediction rules. In: Guyatt G, Rennie D, Meade MO, Cook D. Users’ guide to the medical literature, 3rd edition. New York, NY; MgGraw Hill Medical, 2008:491

Monday, September 9, 2013

Blogs Worth Visiting

There are millions of blogs that one might visit. Locating good ones can be a challenge but here is a list of a few I find useful and interesting.

Marginal Revolution ( This is a site dedicated to economics, but not at all dry or boring. You can find all sorts of interesting ideas and concepts here.
Seth Godin ( This is the person who popularized the ideas of tribes, for which our Chancellor made mention during his Homecoming presentation. Godin offers a wealth of ideas relating to production and effectiveness at work. I find his writing humorous and educational at the same time.
Daring Fireball ( This is a blog which covers Apple in great detail. For the Apple lovers, it is a great source of news and ideas.
Typographie (  Well, this is for the nerds among us. This covers type design, an area I find fascinating as a result of my time as an editor. Who thinks about typefaces? Well, editors do!
Overthinking It ( This is a blog which fact checks where science runs up against popular culture. For example, one recent post compared book length to movie length…
Retraction Watch ( This one is great, for showing you where scientific papers have had to have their information retracted from public dissemination. It shows you where mistakes have been made in publication.
Health Care Law Blog ( this blog is maintained by a lawyer and it addresses a host of issues that range from privacy and security, to ethics and to technology.
Health Care Blog ( this is a widely read independent blog looking at the entire healthcare industry. It will provoke you, not matter what side of the political spectrum you are on.
Coach Lawrence’s Blog ( Bias alert? This is the blog my son keeps for his cross-country and track teams at Hinsdale Central High School (Hinsdale, IL). I just like reading his thoughts and appreciating his approach to coaching at the high-school level.


Tuesday, September 3, 2013

A Few More Interesting New Papers

Devakumar D, Brotherton H, Halbert J, Clarke A, Prost A, Hall J. Taking ethical photos of children for medical and research purposes in low-resource settings: an exploratory qualitative study. BMC Medical Ethics 2013, 14:27 doi:10.1186/1472-6939-14-27
Background: Photographs are commonly taken of children in medical and research contexts. With the increased availability of photographs through the internet, it is increasingly important to consider their potential for negative consequences and the nature of any consent obtained. In this research we explore the issues around photography in low-resource settings, in particular concentrating on the challenges in gaining informed consent.
Methods: Exploratory qualitative study using focus group discussions involving medical doctors and researchers who are currently working or have recently worked in low-resource settings with children.
Results: Photographs are a valuable resource but photographers need to be mindful of how they are taken and used. Informed consent is needed when taking photographs but there were a number of problems in doing this, such as different concepts of consent, language and literacy barriers and the ability to understand the information. There was no consensus as to the form that the consent should take. Participants thought that while written consent was preferable, the mode of consent should depend on the situation.
Conclusions: Photographs are a valuable but potentially harmful resource, thus informed consent is required but its form may vary by context. We suggest applying a hierarchy of dissemination to gauge how detailed the informed consent should be. Care should be taken not to cause harm, with the rights of the child being the paramount consideration.

Cramer H, Lauche R, Langhorst J, Paul A, Michalson A, Dobos G. Predictors of yoga use among internal medicine patients. BMC Complementary and Alternative Medicine 2013, 13:172 doi:10.1186/1472-6882-13-172
Background: Yoga seems to be an effective means to cope with a variety of internal medicine conditions. While characteristics of yoga users have been investigated in the general population, little is known about predictors of yoga use and barriers to yoga use in internal medicine patients. The aim of this cross-sectional analysis was to identify sociodemographic, clinical, and psychological predictors of yoga use among internal medicine patients.
Methods: A cross-sectional analysis was conducted among all patients being referred to a Department of Internal and Integrative Medicine during a 3-year period. It was assessed whether patients had ever used yoga for their primary medical complaint, the perceived benefit, and the perceived harm of yoga practice. Potential predictors of yoga use including sociodemographic characteristics, health behavior, internal medicine diagnosis, general health status, mental health, satisfaction with health, and health locus of control were assessed; and associations with yoga use were tested using multiple logistic regression analysis. Odds ratios (OR) with 95% confidence intervals (CI) were calculated for significant predictors.
Results: Of 2486 participants, 303 (12.19%) reported having used yoga for their primary medical complaint. Of those, 184 (60.73%) reported benefits and 12 (3.96%) reported harms due to yoga practice. Compared to yoga non-users, yoga users were more likely to be 50–64 years old (OR = 1.45; 95%CI = 1.05-2.01; P = 0.025); female (OR = 2.45; 95%CI = 1.45-4.02; P < 0.001); and college graduates (OR = 1.61; 95%CI = 1.14-2.27; P = 0.007); and less likely to currently smoke (OR = 0.61; 95%CI = 0.39-0.96; P = 0.031). Manifest anxiety (OR = 1.47; 95%CI = 1.06-2.04; P = 0.020); and high internal health locus of control (OR = 1.92; 95%CI = 1.38-2.67; P < 0.001) were positively associated with yoga use, while high external-fatalistic health locus of control (OR = 0.66; 95%CI = 0.47-0.92; P = 0.014) was negatively associated with yoga use.
Conclusion: Yoga was used for their primary medical complaint by 12.19% of an internal integrative medicine patient population and was commonly perceived as beneficial. Yoga use was not associated with the patients’ specific diagnosis but with sociodemographic factors, mental health, and health locus of control. To improve adherence to yoga practice, it should be considered that male, younger, and anxious patients and those with low internal health locus of control might be less intrinsically motivated to start yoga.

Kikukawa M, Nabeta H, Ono M, Emura S, Oda Y, Koizumi S, Sakemi T. The characteristics of a good clinical teacher as perceived by resident physicians in Japan: a qualitative study. BMC Medical Education 2013, 13:100 doi:10.1186/1472-6920-13-100

Background: It is not known whether the characteristics of a good clinical teacher as perceived by resident physicians are the same in Western countries as in non-Western countries including Japan. The objective of this study was to identify the characteristics of a good clinical teacher as perceived by resident physicians in Japan, a non-Western country, and to compare the results with those obtained in Western countries.
Methods: Data for this qualitative research were collected using semi-structured focus group interviews. Focus group transcripts were independently analyzed and coded by three authors. Residents were recruited by maximum variation sampling until thematic saturation was achieved.
Results: Twenty-three residents participated in five focus group interviews regarding the perceived characteristics of a good clinical teacher in Japan. The 197 descriptions of characteristics that were identified were grouped into 30 themes. The most commonly identified theme was “provided sufficient support”, followed by “presented residents with chances to think”, “provided feedback”, and “provided specific indications of areas needing improvement”. Using Sutkin’s main categories (teacher, physician, and human characteristics), 24 of the 30 themes were categorized as teacher characteristics, 6 as physician characteristics, and none as human characteristics.
Conclusions: “Medical knowledge” of teachers was not identified as a concern of residents, and “clinical competence of teachers” was not emphasized, whereas these were the two most commonly recorded themes in Sutkin’s study. Our results suggest that Japanese and Western resident physicians place emphasis on different characteristics of their teachers. We speculate that such perceptions are influenced by educational systems, educational settings, and culture. Globalization of medical education is important, but it is also important to consider differences in educational systems, local settings, and culture when evaluating clinical teachers.