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Methacholine Challenge Testing*: Identifying Its Diagnostic Role, Testing, Coding, and Reimbursement FREE TO VIEW

Sam Birnbaum, BBA, CMPE; Timothy J. Barreiro, DO, FCCP
Author and Funding Information

*From the Division of Pulmonary and Critical Care Medicine (Dr. Barreiro), Northeastern Ohio Universities College of Medicine, Ohio University College of Osteopathic Medicine, St. Elizabeth Health Center, Youngstown, OH; and Medical Practice Management (Mr. Birnbaum), Hilton Head Island, SC.

Correspondence to: Sam Birnbaum, BBA, CMPE, 4 Coquina Rd, Hilton Head Island, SC 29928; e-mail: sam@mypracticeconsultant.com



Chest. 2007;131(6):1932-1935. doi:10.1378/chest.06-1385
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Methacholine challenge testing (MCT), also sometimes described as bronchoprovocation testing, is widely performed for both research and diagnostic purposes. MCT is clinically useful when the patient presents with a history of symptoms suggesting asthma, but spirometry findings are normal. Typically, MCT is performed in a pulmonary function laboratory, a clinic, or a physician’s office. MCT requires time, effort, and understanding. Two standard testing regimes are identified along with proper coding and reimbursement methodologies.

The purpose of this article is to provide basic guidelines and suggestions for methacholine challenge testing (MCT). Specifically, this article will review the procedure and indications, suggest several accepted protocols, and outline safety measures. Additionally, patient preparation, proper billing codes, and methodologies for appropriate reimbursement are discussed.

With MCT, the patient inhales an aerosol of one or more concentrations of methacholine.1Methacholine chloride (acetyl-β-methylcholine) is a parasympathomimetic synthetic analog of acetylcholine. It stimulates muscarinic, postganglionic parasympathetic receptors, causing bronchial smooth muscle constriction.2Pharmacy-provided compounded methacholine is not approved by the US Food and Drug Administration, although it has been commonly used for years. Typically, methacholine (Provocholine [approved by the US Food and Drug Administration]; Methapharm; Coral Springs, FL) is used and reconstituted with sterile saline solution or a phenol preservative then is administered via inhalation in gradually increasing concentrations. Pulmonary function testing (eg, serial spirometry or specific airway conductance) is performed before and after each inhalation, and the results are used to quantitate a response. Acceptable spirometric testing is important since poor patient effort is known to produce false-positive results.4 A positive test result is defined as a decrease in the baseline FEV1 of 20% or by a decrease in specific airway conductance of 35 to 45% from baseline. After a positive response, bronchodilators should be administered to assure that lung function has returned to near baseline (ie, at least 85% of baseline).5

Inhaled corticosteroids are prescribed with the goal of suppressing eosinophilic airway inflammation; therefore, MCT should be delayed for several weeks after therapy with inhaled corticosteroids is discontinued. Otherwise, the MCT results may be falsely negative. Patients using bronchodilators should withhold usage prior to MCT based on the medication duration of action.6Patients should avoid coffee, tea, chocolates, or other foods containing caffeine prior to testing.7Other factors that may confound the results include active smoking,8occupational sensitizers, respiratory infections,911 specific allergens,12 and vigorous exercise.

Hazards and reactions include bronchoconstriction, hyperinflation with severe coughing, dizziness, lightheadedness, or chest pain. Nurses or technicians who have asthma should not administer methacholine. The material data safety sheet, which is provided by the manufacturer, must be reviewed by each technician using this agent.

Each laboratory should standardize the procedure.4 Documentation of the results, therapeutic interventions, and clinical decisions should be placed in the patient’s medical record. A list of the patient’s medications, doses, and time the medication was taken prior to testing, and the results of pretest assessment should be documented. Calibration and quality control measures specific to the equipment used for MCT must be implemented.

Many different dosing protocols have been used; each has advantages and disadvantages. The current American Thoracic Society guideline for challenge testing is narrowed down to two protocols1,10: (1) the 2-min tidal breathing method; and (2) the 5-min dosimeter method.

These protocols produce different results.13The tidal breathing method is more sensitive14; quadrupling doses can safely be used, small volumes of Provocholine can be used to reduce cost,15and an expensive dosimeter is not needed.16

Indications for MCT include the need to exclude a diagnosis of airway hyperresponsiveness or hyperactivity. Hyperresponsive airways are one of the key features that contribute to a diagnosis of asthma. History, physical examination, and spirometry have been shown to be poor predictors of hyperresponsive airways.6 The varied clinical presentations of asthma including, wheezing,17high blood total eosinophil count,18and cough19are not specific for the diagnosis of asthma. MCT is often considered in the clinical setting of asthma-like symptoms with normal or near-normal spirometry findings or when the postbronchodilation FEV1 improves but is not greater than 12% and 200 mL.20 While the most common clinical indication for MCT is in patients with a history of asthma-like symptoms but normal spirometry findings, either exhaled nitric oxide or the MCT results can also be used to titrate the daily dose of inhaled corticosteroids or prednisone in patients who are known to have asthma.21MCT also helps in evaluating dyspnea. In a report22 on 85 patients who had been referred for the evaluation of dyspnea, a diagnosis of airway hyperresponsiveness consistent with asthma, was found in 29% of patients based on positive MCT findings. In > 20% of the patients with asthma in this study, physical examination findings and family history did not suggest a positive MCT result in over half of the patients. Thus, clinical predictors of asthma can be deceiving.

MCT is useful in evaluating respiratory symptoms associated or caused by environmental or toxic exposures. MCT is also helpful to determine and monitor patients with environmental exposures and occupational asthma.2324

Bronchial challenge is safe and easy to perform; however, there are contraindications to testing. Contraindications include ventilatory impairment with an FEV1 of < 60% predicted or < 1.5 L and poorly controlled hypertension.25 The rationales are the difficulty in interpreting a “positive” response in the presence of airflow obstruction and the possibility of a dramatic fall in lung function. Other contraindications include the inability to perform acceptable quality spirometry maneuvers and a respiratory infection within the past 6 weeks. Also contraindicated is the current use of cholinesterase inhibitors, pregnancy (from the manufacturer’s instructions for Provocholine use), and women who are lactating.

The primary variable to be monitored is FEV1; the results of spirometry should meet acceptability and reproducibility standards as recommended by American Thoracic Society.3 Testing should be administered according to specific protocols including the number of breaths and breathing patterns documented. MCT is very safe. Bronchospasm due to the test is quickly relieved by inhaled albuterol. When patients experience bronchospasm during MCT (and FEV1 decreases > 20%), there is a tendency for wheezing to occur; oxygen saturation may fall slightly, and the pulse rate may increase slightly. Therefore, BP and pulse rate should be measured and monitored during testing. Patients should not be left unattended during the procedure. In the case of a positive response to provocation, bronchodilators should be administered to speed the recovery. Spirometry should be repeated after bronchodilator administration to ensure that the ventilatory function has returned to near baseline.,26The Centers for Medicare and Medicaid Services (CMS) has identified MCT as level 2 service requiring direct physician supervision. Direct physician supervision requires a physician to be present in the suite and immediately available if needed, but not in attendance during the procedure.27Commercial insurers may have a variety of other requirements regarding physician supervision, and these should be researched on an individual basis.28

Many factors should be taken into account when interpreting the MCT. The pretest probability of asthma, including current symptoms, the presence of baseline airway obstruction, the quality of the spirometric maneuvers, the symptoms reported at the end of the test, and the degree of recovery after bronchodilator administration, should all be considered. Pretest probability is the most important when deciding whether or not someone has asthma.29 MCT is best done when the probability of asthma is 30 to 70%. A positive test result must be interpreted within the context of the clinical probability that the disease is present in the patient tested. The concentration of methacholine causing a 20% fall in FEV1 is the primary MCT outcome measure. A low concentration of methacholine causing a 20% fall in FEV1 (such as 2 mg/mL) confirms the presence of asthma (or poor asthma control), while the lack of a 20% fall in FEV1 at the highest concentration (16 to 32 mg/mL) effectively rules out asthma.

Typically, MCT is performed in a pulmonary function laboratory, a clinic, or a physician’s office.

The CMS reimbursement for MCT is approximately $175. Reimbursement from commercial insurers may vary dramatically. Although CMS guidelines and coding methodologies are generally accepted by most commercial insurers, it is not unusual for some commercial insurers to “bundle” or combine these components into a single reimbursement. It is recommended that individual coverage be researched to determine each patient’s benefit level. It is likely that most patients may be younger and therefore not be Medicare beneficiaries. The Current Procedural Terminology lists the following codes for MCT (both codes should be reported for each procedure): 94070, bronchospasm provocation evaluation, multiple spirometric determinations, as in code 94010, with administered agents (eg, antigen, cold air, or methacholine) [report antigen administration separately with code 99070 or the appropriate supply code]; and 95070, inhalation bronchial challenge testing (not including necessary pulmonary function tests) performed using histamine, methacholine, or similar compounds.

Additionally, the amount of methacholine used must be reported using the appropriate Healthcare Common Procedure Coding System supply code J7674. This should be reported per unit (1 mg) used. Therefore, if 100 mg of the agent is used, 100 U should be reported for appropriate reimbursement. Reimbursement for pharmacy-provided compounded methacholine and/or Provocholine may vary among payers. The dosing protocol will determine the volume of the agent consumed. Thus, the complete coding of MCT would be reported as codes 94070, 95707, and J7674.3031

The Correct Coding Initiative (CCI) established by CMS lists codes 94010, 94060, 94200, 94375, 94640, and 94770 as column I codes, which would preclude billing these with code 94070. The CCI also lists codes 94620, 94621, and 95071 as “mutually exclusive” with code 94070, which precludes billing these on the same day. Furthermore, the CCI identifies codes 94760 and 94791 as column I codes; code 95071 as a column II code; and codes 94010 and 95075 as “mutually exclusive” with code 95070, which precludes billing these on the same day.32

A 49-year-old man was referred for chest tightness and cough lasting 3 weeks. His symptoms are worse in cold weather. He complains of seasonal allergies but takes no medication. He is a nonsmoker with no family history of lung disease. He has no pets. He denies any upper respiratory symptoms or gastroesophageal reflux. Physical examination findings were normal. Baseline spirometry findings were normal. The patient’s pretest probability of asthma is 50%. The patient underwent MCT; FEV1 declined by 26% with a methacholine concentration of 0.25 mg/mL, with complaints of chest tightness. His FEV1 returned to a normal level with the administration of albuterol. Asthma was diagnosed in the patient. Inhaled steroids and allergy-avoidance therapy was started, and his condition improved.

MCT consisted of nine maneuvers of serial spirometry (code 94070) and the actual administration of the inhalation bronchial challenge test (code 95070). The patient received only two doses of Provocholine; however, a total dose of 100 mg was diluted. Therefore, in addition to codes 94070 and 95070, 100 U of code J7674 (Provocholine) should also be reported.

Although the results of history, physical examination, and spirometric testing can support the diagnosis of most lung diseases, MCT may be a useful diagnostic tool in ruling out asthma. It plays a unique role in the evaluation of unexplained cough and/or dyspnea. 33 When initial treatment with bronchodilators does not relieve the patient’s symptoms, MCT should be performed. MCT is underutilized by most clinicians but is a valuable diagnostic tool. MCT is reimbursed by most commercial carriers and Medicare, and is a valuable diagnostic tool that can be used in the physician office setting and other appropriate sites of service.

Abbreviations: CCI = Correct Coding Initiative; CMS = Centers for Medicare and Medicaid Services; MCT = methacholine challenge testing

The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Crapo, RO, Casaburi, R, Coates, AL, et al (2000) Guidelines for methacholine and exercise challenge testing-1999: this official statement of the American Thoracic Society was adopted by the ATS Board of Directors, July 1999.Am J Respir Crit Care Med161,309-329. [PubMed]
 
Beckett, WS, Marenberg, ME, Pace, PE Repeated methacholine challenge produces tolerance in normal but not in asthmatic subjects.Chest1992;102,775-779. [PubMed] [CrossRef]
 
Miller, MR, Hankinson, J, Brusasco, V, et al Standardization of spirometry.Eur Respir J2005;26,319-338. [PubMed]
 
American Thoracic Society.. Standardization of spirometry, 1994 update.Am J Respir Crit Care Med1995;152,1107-1136. [PubMed]
 
Tashkin, DP, Altose, MD, Bleecker, ER, et al The lung health study: airway responsiveness to inhaled methacholine in smokers with mild to moderate airflow limitation: the Lung Health Study Research Group.Am Rev Respir Dis1992;145,301-310. [PubMed]
 
Dales, RE, Nunes, F, Partyka, D, et al Clinical prediction of airways hyperresponsiveness.Chest1988;93,984-986. [PubMed]
 
Henderson, JC, O’Connell, F, Fuller, RW Decrease of histamine induced bronchoconstriction by caffeine in mild asthma.Thorax1993;48,824-826. [PubMed]
 
Jensen, EJ, Dahl, R, Steffensen, F Bronchial reactivity to cigarette smoke in smokers: repeatability, relationship to methacholine reactivity, smoking and atopy.Eur Respir J1998;11,670-676. [PubMed]
 
Empey, DW, Laitinen, LA, Jacobs, L, et al Mechanisms of bronchial hyperreactivity in normal subjects after upper respiratory tract infection.Am Rev Respir Dis1976;113,131-139. [PubMed]
 
Sterk, PJ, Fabbri, LM, Quanjer, PH, et al Airway responsiveness: standardized challenge testing with pharmacological, physical and sensitizing stimuli in adults: Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal; official Statement of the European Respiratory Society.Eur Respir J Suppl1993;16,53-83. [PubMed]
 
Sterk, PJ Bronchial hyperresponsiveness today.Respir Med1993;87(suppl),27-29
 
Cockcroft, DW, Davis, BE, Boulet, LP, et al The links between allergen skin test sensitivity, airway responsiveness and airway response to allergen.Allergy2005;60,56-59. [PubMed]
 
Allen, ND, Davis, BE, Hurst, TS, et al Difference between dosimeter and tidal breathing methacholine challenge: contributions of dose and deep inspiration bronchoprotection.Chest2005;128,4018-4023. [PubMed]
 
Cockcroft, DW, Davis, BE The bronchoprotective effect of inhaling methacholine by using total lung capacity inspirations has a marked influence on the interpretation of the test result.J Allergy Clin Immunol2006;117,1244-1248. [PubMed]
 
Cockcroft, DW, Davis, BE, Smycniuk, AJ Development of a methacholine challenge method to minimize methacholine waste.Chest2003;124,1522-1525. [PubMed]
 
Khan, YR, McDonough, P, Cockcroft, DW, et al Nebulizer output for methacholine challenges with the KoKo Digidoser.J Allergy Clin Immunol2005;116,924-926. [PubMed]
 
King, DK, Thompson, BT, Johnson, DC Wheezing on maximal forced exhalation in the diagnosis of atypical asthma: lack of sensitivity and specificity.Ann Intern Med1989;110,451-455. [PubMed]
 
Desjardins, A, de Luca, S, Cartier, A, et al Nonspecific bronchial hyperresponsiveness to inhaled histamine and hyperventilation of cold dry air in subjects with respiratory symptoms of uncertain etiology.Am Rev Respir Dis1988;137,1020-1025. [PubMed]
 
Pratter, MR Overview of common causes of chronic cough: ACCP evidence-based clinical practice guidelines.Chest2006;129(suppl),59S-62S
 
Goldstein, MF, Pacana, SM, Dvorin, DJ, et al Retrospective analyses of methacholine inhalation challenges.Chest1994;105,1082-1088. [PubMed]
 
Taylor, DR Nitric oxide as a clinical guide for asthma management.J Allergy Clin Immunol2006;117,259-262. [PubMed]
 
Pratter, MR, Curley, FJ, Dubois, J, et al Cause and evaluation of chronic dyspnea in a pulmonary disease clinic.Arch Intern Med1989;149,2277-2282. [PubMed]
 
Dodge, R Sensitivity of methacholine testing in occupational asthma.Chest1986;89,324-325. [PubMed]
 
Kennedy, SM, Contreras, GR Measurement of nonspecific bronchial responsiveness in epidemiologic studies: methacholine challenge testing in the field.Occup Med1993;8,303-321. [PubMed]
 
Martin, RJ, Wanger, JS, Irvin, CG, et al Methacholine challenge testing: safety of low starting FEV1: Asthma Clinical Research Network (ACRN).Chest1997;112,53-56. [PubMed]
 
Wanger, J, Irvin, CG Office spirometry: equipment selection and training of staff in the private practice setting.J Asthma1997;34,93-104. [PubMed]
 
Centers for Medicare and Medicaid Services, US Department of Health and Human Services. CMS manual system. Available at: http://www.cms.hhs.gov/Transmittals/Downloads/R51BP.pdf#search=%22cms%20physican%20supervision%20regulations%22. Accessed September 12, 2006.
 
Wanger, J Quality assurance.Respir Care Clin N Am1997;3,273-289. [PubMed]
 
Perpina, M, Pellicer, C, de Diego, A, et al Diagnostic value of the bronchial provocation test with methacholine in asthma: a Bayesian analysis approach.Chest1993;104,149-154. [PubMed]
 
 Appropriate Coding for Critical Care Services and Pulmonary Medicine, 2006 Update. 2006; ,.:128 -131 American College of Chest Physicians. Northbrook, IL:.
 
 Appropriate Coding for Critical Care Services and Pulmonary Medicine, 2006 Update. 2006; ,.:178 -180 American College of Chest Physicians. Northbrook, IL:.
 
Centers for Medicare and Medicaid Services, US Department of Health and Human Services. Correct coding initiative. Available at: http://www.cms.hhs.gov/NationalCorrectCodInitEd/. Accessed September 12, 2006.
 
Irwin, RS Introduction to the diagnosis and management of cough: ACCP evidence-based clinical practice guidelines.Chest2006;129(suppl),25S-27S
 

Figures

Tables

References

Crapo, RO, Casaburi, R, Coates, AL, et al (2000) Guidelines for methacholine and exercise challenge testing-1999: this official statement of the American Thoracic Society was adopted by the ATS Board of Directors, July 1999.Am J Respir Crit Care Med161,309-329. [PubMed]
 
Beckett, WS, Marenberg, ME, Pace, PE Repeated methacholine challenge produces tolerance in normal but not in asthmatic subjects.Chest1992;102,775-779. [PubMed] [CrossRef]
 
Miller, MR, Hankinson, J, Brusasco, V, et al Standardization of spirometry.Eur Respir J2005;26,319-338. [PubMed]
 
American Thoracic Society.. Standardization of spirometry, 1994 update.Am J Respir Crit Care Med1995;152,1107-1136. [PubMed]
 
Tashkin, DP, Altose, MD, Bleecker, ER, et al The lung health study: airway responsiveness to inhaled methacholine in smokers with mild to moderate airflow limitation: the Lung Health Study Research Group.Am Rev Respir Dis1992;145,301-310. [PubMed]
 
Dales, RE, Nunes, F, Partyka, D, et al Clinical prediction of airways hyperresponsiveness.Chest1988;93,984-986. [PubMed]
 
Henderson, JC, O’Connell, F, Fuller, RW Decrease of histamine induced bronchoconstriction by caffeine in mild asthma.Thorax1993;48,824-826. [PubMed]
 
Jensen, EJ, Dahl, R, Steffensen, F Bronchial reactivity to cigarette smoke in smokers: repeatability, relationship to methacholine reactivity, smoking and atopy.Eur Respir J1998;11,670-676. [PubMed]
 
Empey, DW, Laitinen, LA, Jacobs, L, et al Mechanisms of bronchial hyperreactivity in normal subjects after upper respiratory tract infection.Am Rev Respir Dis1976;113,131-139. [PubMed]
 
Sterk, PJ, Fabbri, LM, Quanjer, PH, et al Airway responsiveness: standardized challenge testing with pharmacological, physical and sensitizing stimuli in adults: Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal; official Statement of the European Respiratory Society.Eur Respir J Suppl1993;16,53-83. [PubMed]
 
Sterk, PJ Bronchial hyperresponsiveness today.Respir Med1993;87(suppl),27-29
 
Cockcroft, DW, Davis, BE, Boulet, LP, et al The links between allergen skin test sensitivity, airway responsiveness and airway response to allergen.Allergy2005;60,56-59. [PubMed]
 
Allen, ND, Davis, BE, Hurst, TS, et al Difference between dosimeter and tidal breathing methacholine challenge: contributions of dose and deep inspiration bronchoprotection.Chest2005;128,4018-4023. [PubMed]
 
Cockcroft, DW, Davis, BE The bronchoprotective effect of inhaling methacholine by using total lung capacity inspirations has a marked influence on the interpretation of the test result.J Allergy Clin Immunol2006;117,1244-1248. [PubMed]
 
Cockcroft, DW, Davis, BE, Smycniuk, AJ Development of a methacholine challenge method to minimize methacholine waste.Chest2003;124,1522-1525. [PubMed]
 
Khan, YR, McDonough, P, Cockcroft, DW, et al Nebulizer output for methacholine challenges with the KoKo Digidoser.J Allergy Clin Immunol2005;116,924-926. [PubMed]
 
King, DK, Thompson, BT, Johnson, DC Wheezing on maximal forced exhalation in the diagnosis of atypical asthma: lack of sensitivity and specificity.Ann Intern Med1989;110,451-455. [PubMed]
 
Desjardins, A, de Luca, S, Cartier, A, et al Nonspecific bronchial hyperresponsiveness to inhaled histamine and hyperventilation of cold dry air in subjects with respiratory symptoms of uncertain etiology.Am Rev Respir Dis1988;137,1020-1025. [PubMed]
 
Pratter, MR Overview of common causes of chronic cough: ACCP evidence-based clinical practice guidelines.Chest2006;129(suppl),59S-62S
 
Goldstein, MF, Pacana, SM, Dvorin, DJ, et al Retrospective analyses of methacholine inhalation challenges.Chest1994;105,1082-1088. [PubMed]
 
Taylor, DR Nitric oxide as a clinical guide for asthma management.J Allergy Clin Immunol2006;117,259-262. [PubMed]
 
Pratter, MR, Curley, FJ, Dubois, J, et al Cause and evaluation of chronic dyspnea in a pulmonary disease clinic.Arch Intern Med1989;149,2277-2282. [PubMed]
 
Dodge, R Sensitivity of methacholine testing in occupational asthma.Chest1986;89,324-325. [PubMed]
 
Kennedy, SM, Contreras, GR Measurement of nonspecific bronchial responsiveness in epidemiologic studies: methacholine challenge testing in the field.Occup Med1993;8,303-321. [PubMed]
 
Martin, RJ, Wanger, JS, Irvin, CG, et al Methacholine challenge testing: safety of low starting FEV1: Asthma Clinical Research Network (ACRN).Chest1997;112,53-56. [PubMed]
 
Wanger, J, Irvin, CG Office spirometry: equipment selection and training of staff in the private practice setting.J Asthma1997;34,93-104. [PubMed]
 
Centers for Medicare and Medicaid Services, US Department of Health and Human Services. CMS manual system. Available at: http://www.cms.hhs.gov/Transmittals/Downloads/R51BP.pdf#search=%22cms%20physican%20supervision%20regulations%22. Accessed September 12, 2006.
 
Wanger, J Quality assurance.Respir Care Clin N Am1997;3,273-289. [PubMed]
 
Perpina, M, Pellicer, C, de Diego, A, et al Diagnostic value of the bronchial provocation test with methacholine in asthma: a Bayesian analysis approach.Chest1993;104,149-154. [PubMed]
 
 Appropriate Coding for Critical Care Services and Pulmonary Medicine, 2006 Update. 2006; ,.:128 -131 American College of Chest Physicians. Northbrook, IL:.
 
 Appropriate Coding for Critical Care Services and Pulmonary Medicine, 2006 Update. 2006; ,.:178 -180 American College of Chest Physicians. Northbrook, IL:.
 
Centers for Medicare and Medicaid Services, US Department of Health and Human Services. Correct coding initiative. Available at: http://www.cms.hhs.gov/NationalCorrectCodInitEd/. Accessed September 12, 2006.
 
Irwin, RS Introduction to the diagnosis and management of cough: ACCP evidence-based clinical practice guidelines.Chest2006;129(suppl),25S-27S
 
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