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OnTrak TesTstik 2 for Cocaine/THC is an in vitro diagnostic test intended for professional use for the qualitative detection of cocaine metabolite and cannabinoids in urine. The OnTrak TesTstik 2 for Cocaine/THC cutoff levels (300 ng/ml for cocaine and 50 ng/ml for THC) are based on the Federal Mandatory Guidelines. OnTrak TesTstik 2 for Cocaine/THC is not intended for over-the-counter sale.

OnTrak TesTstik provides only a preliminary analytical test result. A more specific alternate chemical method must be used in order to obtain a confirmed analytical result. Gas chromatography/mass spectrometry (GC/MS) is the preferred confirmation method. Clinical consideration and professional judgment should be applied to any drug of abuse test result, particularly when preliminary positive results are used.

The OnTrak TesTstik 2 Cocaine/THC assay described in this submission is an in vitro test intended for professional use in the qualitative detection of cocaine metabolite and cannabinoids in urine at or above a cutoff concentration of 300 ng/ml (cocaine) and 50 ng/ml (THC).

The TesTstik assays are based on the principle of microparticle capture inhibition. The test relies on the competition between drug, which may be present in the urine being tested, and drug conjugate immobilized on a membrane.

When the TesTstik is immersed in the urine sample, some of the sample is absorbed into the TesTstik sample pad. The absorbed sample travels through a reagent strip contained in the device by capillary action. In the reagent strip, the sample rehydrates and mobilizes antibody-coated blue microparticles. The microparticle-urine suspension continues to migrate through the reagent strip and comes in contact with the immobilized drug conjugate. In the absence of drug in the urine, the antibody-coated microparticles bind to the drug conjugates and blue bands are formed at the result window ("negative" sign).

When drug is present in the specimen, it binds to the antibody-coated microparticles. If sufficient drug is present, the micro-particles are inhibited from binding the drug conjugate and no blue band is formed at the result window. A positive sample caused the membrane to remain white.

An additional antibody/antigen reaction occurs at the "TEST VALID" area. The "TEST VALID" blue band forms when antibodies, which are imbedded in the reagent membrane, bind to the antigen on the blue microparticles. The presence of the "TEST VALID" band indicates that the test has completed, the reagents in the TEST VALID area are viable, and the results are ready to interpret.

This K994164 submission describes a new device, OnTrak TesTstik™ 2 for Cocaine/THC, and claims substantial equivalence to two predicate devices, OnTrak TesTstik for Cocaine and OnTrak TesTstik for THC (both cleared under K973075).

Here's an analysis of the acceptance criteria and the study that proves the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance

2. Sample Size Used for the Test Set and Data Provenance

• Cocaine:

  • Positive Specimens: 70 clinical specimens, including near cutoff specimens.
  • Negative Specimens: 100 urine specimens from a clinical laboratory (screened negative by automated immunoassay), with 15% confirmed negative by GC/MS.
  • Data Provenance: Clinical specimens obtained from a clinical laboratory; the country of origin is not specified but implicitly in the USA, where the submitter is located. The data is retrospective as it refers to "clinical specimens screened" and "obtained from a clinical laboratory."

• THC:

  • Positive Specimens: 70 clinical specimens, including near cutoff specimens.
  • Negative Specimens: 100 urine specimens from a clinical laboratory (screened negative by automated immunoassay), with 15% confirmed negative by GC/MS.
  • Data Provenance: Clinical specimens obtained from a clinical laboratory; the country of origin is not specified but implicitly in the USA. The data is retrospective.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications

The document does not specify the number or qualifications of experts directly establishing the ground truth. Instead, it relies on established laboratory methods:

• For positive specimens: Initially screened by an automated immunoassay, and then confirmed positive by GC/MS. GC/MS (Gas Chromatography/Mass Spectrometry) is a highly accurate and widely accepted "gold standard" for drug confirmation in toxicology.
• For negative specimens: Screened negative by automated immunoassays, and a portion (15%) confirmed negative by GC/MS.

Therefore, the ground truth is established by a combination of automated immunoassay screening and confirmatory GC/MS, rather than a human expert panel.

4. Adjudication Method for the Test Set

There is no mention of an adjudication method involving human consensus for the test set results. The comparison is made directly against the "ground truth" established by laboratory methods (GC/MS for confirmation).

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No MRMC study was performed or mentioned. This type of study (human readers with/without AI assistance) is not relevant for this in-vitro diagnostic device, which is an automated or semi-automated test reading designed for professional use. The performance evaluation focuses on the device's accuracy against laboratory standards.

6. Standalone (Algorithm Only) Performance

Yes, a standalone performance study was done. The document details the "OnTrak TesTstik 2 for Cocaine/THC was evaluated using clinical specimens" and directly reports its agreement percentages (94% for Cocaine, 95% for THC) against the ground truth established by GC/MS and predicate comparison. This evaluation is of the device's intrinsic performance without human interpretation or assistance beyond loading the sample.

7. The Type of Ground Truth Used

The primary type of ground truth used is GC/MS (Gas Chromatography/Mass Spectrometry), which is considered a definitive confirmatory method in toxicology. This is supplemented by initial screening with an automated immunoassay.

8. The Sample Size for the Training Set

The document does not provide information about a "training set" or its size. In a 510(k) submission for a diagnostic test like this, the focus is on the performance of the finalized device (the "test set" in your query context) rather than detailing developmental training data. This implies a traditional assay development workflow rather than a machine learning model that would require explicit training and validation sets.

9. How the Ground Truth for the Training Set Was Established

As no training set is described, the method for establishing its ground truth is not applicable/mentioned.

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