Thursday, November 1, 2018

Appendectomy outcomes in the modern era

Finally we have some data on the current rate of complications of appendectomy for uncomplicated appendicitis. But that’s not all. This new paper, published online in the journal Surgery, reveals much about the diagnosis, technique, and outcomes of appendectomy in the United States.

Using data from 115 hospitals participating in the National Surgical Quality Improvement Program, researchers at UCLA analyzed the results of 7778 adult patients undergoing appendectomy for simple appendicitis in 2016.

Thursday, October 4, 2018

A Venezuelan surgical resident appeals for help

I received the following email. It has been edited for length and readability.

I assume you know is happening in my country, Venezuela. Basically a communist-socialist party has taken control of the government for 20 years now and has the citizens under the worst economic crisis of South America along with one of the most important refugee situations of the continent.

I can write 300 pages about it, but I believe I’ve said enough. As you may know, EVERYTHING has gone to bad situations in this country: public services, roads, HOSPITALS, UNIVERSITIES, food shortage, lack of water and electricity, freedom of speech, and the list goes on and on.

Tuesday, October 2, 2018

A Revolutionary Experience!

Listen as renowned surgeon Leo Gordon reads his epic story about pancreatic insufficiency and the American Revolution. Based on a true story. The podcast is 15 minutes long and worth every second of it.

Wednesday, September 19, 2018

“Number of medical students pursuing surgery specialty drops by half”

That was the headline in a September 10 Becker’s ACS Review article. The first sentence of the piece was more specific, “Only 4 percent of medical students surveyed in 2018 said their chosen medical specialty is general surgery, compared with 8 percent in 2016, according to Medscape's Medical Student Life & Education Report 2018.”

This caused some consternation among general surgeons on Twitter. I tweeted, “Interesting. Lifestyle is finally catching up to us. I think it will get worse.”

Thursday, September 6, 2018

How to interpret the literature: A new series of posts

The Salty Statistician will be a recurring feature of this blog wherein we ask statisticians in medicine to break down articles from the surgery literature and assess whether the reported conclusions are supported by the data. Let’s look at this study:

Groh MA et al. Is Surgical Intervention the Optimal Therapy for the Treatment of Aortic Valve Stenosis for Patients With Intermediate Society of Thoracic Surgeons Risk Score? Annals of Thoracic Surgery.

The authors attempted to address the question of whether aortic stenosis patients deemed “intermediate risk” [IR] for surgical aortic valve replacement [AVR] are best treated with open surgery or transcatheter AVR. The authors looked at 1,144 patients who received surgical AVR from 2008-2014 at a single center focusing on the 620 “intermediate risk” patients. At the end of the follow-up period, 72 had died.

Unfortunately, major methodological issues undermine the paper’s conclusions. Fortunately, this provides an excellent teaching opportunity.

First, the authors inappropriately used logistic regression to analyze independent predictors of mortality. Logistic regression treats the outcome as a simple “Yes” or “No” variable, while ignoring the time-at-risk. This study included patients treated over a six-year period (2008-2014) who therefore have substantial differences in the amount of time at risk. Consider the following hypothetical patients.

Patient A treated in 2008 and died in 2014 surviving six years after surgery. The logistic regression model simply counts patient A as “dead.”

Patient B treated in 2014 and alive in 2017 but dies in 2018, after the data were analyzed and the paper published. He survived four years after surgery and in the logistic regression model, counts as “alive” since data were analyzed in 2017.

Patient A lived for six years after surgery, but counts as “worse” in the analysis than Patient B who only lived for four years because of the time at which the data were “frozen” and analyzed. Of course, this is unavoidable in long-term outcomes studies, but one must choose an appropriate statistical method that accounts for time-at-risk.

Cox proportional-hazards models are more appropriate for a long-term survival outcome than logistic regression. When building a Cox model, one specifies both the current status (i.e., alive/dead) as well as an amount of follow-up time. For example, Patient A is “dead” with six years of follow-up; Patient B is “alive” but with only three years of follow-up. This provides a proper assessment of how strongly the independent variables are associated with risk of mortality while accounting for the unequal follow-up time.

Second, the authors state their data supports the conclusion that “SAVR is the optimal therapy for most of the patients” in the IR group in comparison to TAVR. However, their paper lacks any data on outcomes in IR patients who were treated with TAVR. Why the authors believe presenting data from a series of SAVR patients is sufficient to claim that SAVR is the “optimal therapy” absent any comparison data on patients treated with TAVR is unclear. Randomized controlled trials have more appropriately compared SAVR and TAVR in the IR population. Link here and here.

Which patients should receive surgical AVR versus transcatheter AVR is a good question, but to answer it, the paper used an incorrect approach.

Final Rating (1-5 Scalpels): 1 Scalpel - significant methodological issues

This issue of the Salty Statistician was written by Andrew Althouse (@ADAlthousePhD), currently an Assistant Professor of Medicine at the University of Pittsburgh as well as Statistical Editor of Circulation: Cardiovascular Interventions.

We intend this series to focus on work that is perceived to have a high impact on clinical practice, so we welcome reader suggestions. If you have a paper that you would like to see reviewed as part of the Salty Statistician series, please tweet @Skepticscalpel or @ADAlthousePhD or email We cannot promise that all submissions will be reviewed in this space, but we will do our best.

Thursday, August 23, 2018

A perforated colon case report raises a few issues

When a medical paper is featured on the Daily Mail website, you know it’s going to be something odd.

An autistic young man with prior hospitalizations for chronic constipation and megacolon was admitted to a hospital in London, UK with a markedly distended abdomen. A CT scan showed a dilated rectum and colon with a diameter as large as 18 cm (7 inches).

He was treated conservatively for two days with laxatives. Enemas were ordered, but the patient declined. He then developed peritonitis, kidney dysfunction, mental status changes, and metabolic acidosis.

Friday, August 17, 2018

Patient worries after accessing his chest x-ray report online

I received an email a few days ago. It has been edited for length and clarity.

I would like some advice please. I am a 46-year-old male with an off and on cough for 4-5 months. I have never smoked. After my primary care physician examined me, he ordered a chest x ray. A few days later I got a call from the doctor who said my x ray was normal. I was happy to hear that, but I am enrolled with My Chart which allows you to review your results online. Well, I read it and to me it doesn't sound what you would call totally normal, but I have no medical training so I could be wrong. I copied and pasted the report from the radiologist below. What concerns me is the "elevation" he refers to and using the word "fairly" clear lungs. Should I ask for another test or see another doctor for an opinion? If I was your family member would you suggest looking into this more?


FINDINGS: The frontal view demonstrates fairly clear lungs with slightly increased elevation of the left hemidiaphragm compared with the prior study. This may be at least partially caused by air in the adjacent bowel. No pleural effusion or pneumothorax is noted. The cardiomediastinal silhouette is unremarkable. The lateral view demonstrates fairly stable appearance of the lung bases compared with the previous study.