Do I really need that test?

Medical testing for diagnosis and disease monitoring become sort of a routine part of a Crohn's patient's life.  These tests run the gamut from less-invasive blood and stool tests and diagnostic imaging to invasive colonoscopies.  I am particularly interested in the research on appropriate clinical testing for Crohn's activity, for both the personal reason of balking every time my gastroenterologist recommends another colonoscopy, and because I think the "right" amount of testing is an extremely complicated issue for any doctor and patient to work out.  The reasons for this are muti-fold... sometimes the incentives for testing are not in the right place, the tort* culture of medicine in the US makes it so that missing a diagnosis or complication is a major concern for physicians, and personal anecdotes and experience heavily influence human decisions (and doctors are not immune to this fact).  This is not to say that physicians just order tests all willy-nilly.  Most doctors are well aware of the costs associated with over testing... both the indirect costs of inflating health care expenditures and the direct costs to the patient of potentially identifying "incidentalomas" (An incidentaloma is essentially a made-up term to describe some test finding that would have never caused any problems for the patient, but because it is discovered by a clinical test, it necessitates even more testing and evaluation... e.g., a benign mass that is identified by MR imaging.).  Also, despite the fact that evidence-based medicine* is the ideal for practice, every patient situation is unique, and controlled research studies cannot possibly address every scenario, which sometimes makes it hard for the clinician to make decisions solely on research conclusions.

A note to keep in mind...

For the record, it was difficult to find research the topic of testing indications during Crohn's management.  I found many articles on standard-of-care* guidelines for Crohn's treatments, but as for recommendations and indications for testing, there was shockingly little.  From the standpoint of controlling health care costs, this is fairly problematic... many doctors could be ordering unnecessary tests and driving up costs, simply because there's limited to no data to show that those tests are unnecessary... the research just isn't there.  That being said, I will review what publications I could find on the matter, and I will continue to follow the literature on this issue for updates.

Testing at the time of diagnosis

The diagnosis of Crohn's disease usually relies on the results from a number of different tests... including endoscopy, biopsy, blood, and diagnostic imaging results (Mowat et al. 2011).  The key finding for Crohn's diagnosis is generally a specific pattern of inflammation on endoscopy and biopsy, which distinguish it from other forms of inflammatory bowel disease ("skip lesions" and "granulomatous" inflammation... I will discuss these in detail in future posts), and the rest of the test results support the clinical picture, establish a baseline for disease activity at the time of diagnosis, and determine whether any complications are present.

Other situations when testing is (absolutely) necessary

I qualify "absolutely" because I struggle with saying that anything is ever definitive or true in all cases, but there are other situations in which testing definitely meets criteria for being the standard of care for Crohn's management.  When there is a dramatic change in Crohn's symptoms that is suggestive of an acute complication... for example, a sudden uptick in pain or blood loss or a striking decrease in frequency of bowel movements (BMs)... diagnostic testing, which will depend on the symptoms, is warranted.  As an aside, using the term BM always makes me think of one of Tina Fey's hilarious quotes from 30 Rock: "Boy, is anybody else BMing like a rock star?".  I think Crohn's patients should use this phrase gratuitously whenever their GI symptoms are in check.

Screening and surveillance colonoscopies are also recommended for patients following diagnosis, due to the increased risk of colon cancer in patients with Crohn's.  Friedman and colleagues followed 259 patients with Crohn's colitis for nearly 17 years, and found that 7% of these individuals had pre-cancerous or cancerous lesions on colonoscopy at some point over the evaluation period (Friedman et al. 2008).  In another study from Sweden, Crohn's patients were found to be at 2.5x increased risk of colon cancer compared with the general population, and that risk increased to 5.6x if the disease involvement was restricted to the colon (Ekbom et al. 1990).

The Crohn's & Colitis Foundation of America recommendations for colonoscopic cancer surveillance are as follows (Farraye et al. 2010):

• Patients with Crohn's disease with major colonic involvement (at least 1/3 of the colon) should have a screening colonoscopy at 8-10 years after disease onset (from start of symptoms... not diagnosis).
• The details of the second recommendation are somewhat complicated and confusing... but basically, if there are no pre-cancerous or cancerous lesions detected on the aforementioned screening colonoscopy, then surveillance colonoscopies should be done every 1-2 years.

Following up for therapeutic response

As for testing to monitor response to therapy, I thought I'd seek answers from clinical trial end points... i.e. what measures do clinical trials use to evaluate the efficacy of therapy?  Many trials use activity scores, such as the Crohn's Disease Activity Index* (CDAI) or Inflammatory Bowel Disease Questionnaire* (IBDQ), in order to measure patients' symptoms before and after therapy (Colombel et al. 2007., Feagan et al. 2008.).  These trials measured response as a decrease in the CDAI (by greater than or equal to 70 points) or as remission by CDAI (score less than or equal to 150).  C-reactive protein (CRP... see my previous post for a more detailed explanation on this blood marker) were also measured from patients in these trials, but this test was not used as an end point to evaluate drug response.  Currently, there isn't a clear precedent for using more invasive testing for monitoring response to therapy, but recommendations for endoscopic disease monitoring are contested (Rameshshanker and Arebi. 2012).

Concluding thoughts

While the gastoenterologist is going to be the expert, and, thus, the most informed person when it comes to making decisions about clinical testing, it is perfectly valid as a patient to have a discussion with your GI doc about his/her reasons for ordering that test and if it's absolutely necessary.  Generally, the litmus test for whether or not a clinical test is needed is based on the question, "Will the results of this test change the patient managment?".  If the answer is "no", then the test shouldn't be done, but if it is "yes" or "potentially", the test is often warranted.  But there are situations in which even this litmus test breaks down... what if a similar answer can be provided by a less-invasive test or just by watchful symptom evaluation over time?  Often things are not clear cut, and the patient and clinician should reach a mutually agreed upon decision for management.

Bibliography:

Colombel et al. (2007) Adalimumab for maintenance of clinical response and remission in patients with Crohn's disease: the CHARM trial. Gastroenterology 132:52-65.

Ekbom et al. (1990) Increased risk of large-bowel cancer in Crohn's disease with colonic involvement. Lancet 336:357-359.

Farraye et al. (2010) AGA technical review on the diagnosis and management of colorectal neoplasia in inflammatory bowel disease. Gastroenterology 138:746-774.

Feagan et al. (2008) Treatment of active Crohn's disease with MLN0002, a humanized antibody to the alpha4beta7 integrin. Clinical Gastroenterology and Hepatology 6:1370-1377.

Friedman et al. (2008) Screening and surveillance colonoscopy in chronic crohn's colitis: results of a surveillance program spanning 25 years. Clinical Gastroenterology and Hepatology 6:993-998.

Mowat et al. (2011) Guidelines for the management of inflammatory bowel disease in adults. Gut 60:571-607.

Rameshshanker and Arebi. (2012) Endoscopy in inflammatory bowel disease when and why. World Journal of Gastrointestinal Endoscopy 4:201-211.

*Some more thorough terminology explanations:

Crohn's Disease Activity Index (CDAI): The CDAI is essentially a way to more-or-less objectively rate the activity of Crohn's disease and is used as a tool for research investigations.  Most clinical trials to evaluate Crohn's therapies will use the CDAI to determine efficacy.  Several symptomatic factors are included into the CDAI computation, including number of stools per day, presence of complications, and general well-being.

Evidence-based medicine: The application of evidence obtained from scientific investigations to clinical decision making.  The goal of evidence-based medicine is to allow a clinician to make decisions about a particular testing or treatment strategy based on controlled studies in large populations instead of purely on personal experience, which can often be biased.  Evidence from controlled investigations can more accurately inform practice about the benefits and harms of a particular clinical strategy, and leads to may recommendations for standard-of-care (see below) practice.

Inflammatory Bowel Disease Questionnaire (IBDQ): This is a questionnaire for IBD activity that incorporates questions to assess the impact that the disease has on quality-of-life factors, such as social and emotional effects.  IBDQ scores generally correlate well with CDAI scores.

Standard of care: A medical treatment guideline that specifies the appropriate testing or treatment based on scientific evidence and the consensus of medical professionals.

Tort: Tort law is a type of jurisdiction that deals with situations in which one person's actions have unfairly caused another individual to suffer loss or harm... so that the harmed individual can recover his/her loss.  Applied to the health care field, tort law generally comes into play in the form of medical malpractice (where a doctor's negligence has caused a patient harm, and the patient or patient's family aims to recoup the costs of that harm).  Claims for medical malpractice must establish all four elements of the tort of negligence in order to be successful.