English[ edit ] Two negatives resolving to a positive[ edit ] When two negatives are used in one independent clause, in standard English the negatives are understood to cancel one another and produce a weakened affirmative:: However, depending on how such a sentence is constructed, in some dialects if a verb or adverb is in between two negatives then the latter negative is assumed to be intensifying the former thus adding weight or feeling to the negative clause of the sentence. For this reason, it is difficult to portray double negatives in writing as the level of intonation to add weight in one's speech is lost. A double negative intensifier does not necessarily require the prescribed steps, and can easily be ascertained by the mood or intonation of the speaker.
Urine drug screening is a common way to test for compliance with medications having high abuse potential.
False-negatives and false-positives from immunoassays can lead to adverse consequences for patients and providers. By identifying medications that contribute to false-negatives and false-positives, pharmacists decrease misinterpretations from urine drug screens.
Unexpected results from urine immunoassays should have a confirmatory gas chromatography—mass spectrometry or a high-performance liquid chromatography test performed. Pharmacists can provide guidance in selecting appropriate drug therapies that are less likely to cause false readings, thus decreasing the need for additional testing.
The most frequently used type of UDS is the immunoassay due to its low cost, rapidity of results, and simplicity of use. Immunoassays detect substances above a set threshold using antibodies. Interpreting Test Results Misinterpretation of UDS results may have adverse consequences for patients, including unwarranted loss of a job, potential criminal charges, loss of qualification from sporting events or rehabilitation programs, potentially improper medical treatment, or loss of trust from healthcare professionals.
When a negative screening result is obtained, pharmacists should carefully consider the potential for a false-negative result, especially for patients receiving UDS testing to assess compliance with a medication regimen or for those exhibiting behaviors or risk factors suggestive of drug abuse or drug dependency.
Patients may also drink an excessive amount of water qt or use diuretics to purposefully dilute their urine and the urine drug Positive and negatives of being a to decrease the chance of detection. For example, UDS tests for benzodiazepines commonly result in false-negatives for agents that have poor cross-reactivity with the assay.
Similarly, opiates can be at risk for false-negatives. Most immunoassay tests look for morphine, norcodeine, and codeine; thus morphine, heroin, and codeine can easily be detected.
Hydrocodone and hydromorphone are metabolites of codeine and are rarely positive on immunoassay tests. Oxycodone, buprenorphine, and tramadol follow a separate metabolic pathway, and fentanyl may not be detected because it lacks metabolites.
Immunoassays test for amphetamines; thus, amphetamine, dextroamphetamine, and lisdexamfetamine products should return positive results for compliance testing if taken in the last 2 to 3 days.
Illicit methamphetamine will also show positive within the amphetamine immunoassay test. However, methylphenidate products do not cross-react with amphetamines and will commonly produce negative results,8 although a false-positive result with methylphenidate has been seen in one pediatric case report.
In addition to false-negatives, pharmacists need to consider the potential for false-positive UDS results and be aware of medications that may cause false-positives.
TABLE 2 summarizes many medications that have been reported to cause false-positive results with common substances of abuse or tricyclic antidepressants TCAs.
The selection of an appropriate therapeutic agent for a patient depends on numerous factors, such as the effectiveness and adverse-effect profile of the drug; therefore, minimizing the use of medications shown to cause false-positives must be weighed against clinical judgment in product selection.
However, for patients undergoing frequent UDS testing, selecting an agent least likely to cause false-positives would be an important consideration to help minimize adverse consequences to patients from potentially misinterpreted results. Antidepressants Many of the medications reported to cause false-positive UDS results include a variety of antidepressants, which can be used for various indications.
Of the selective serotonin reuptake inhibitors SSRIssertraline has been reported to cause false-positive results for benzodiazepines and lysergic acid diethylamide LSD ,9 and fluoxetine has been reported to cause false-positive results for LSD and amphetamines.
Amitriptyline, desipramine, doxepin, and imipramine have been reported to cause false-positive results for LSD,3 and desipramine and doxepin have additionally been reported to cause false-positive results for amphetamines.
For patients requiring an SSRI, pharmacists should consider using paroxetine, citalopram, or escitalopram and minimizing the use of fluoxetine and sertraline when appropriate.
When using an antidepressant to treat neuropathic pain, minimizing the use of venlafaxine and TCAs and instead using duloxetine should be considered. Gabapentin and pregabalin have a minimal risk of causing false-positives and are other options that could be used.
Trazodone is an antidepressant frequently used as a sleep aid. Minimizing its use and instead using mirtazapine or sedative-hypnotics when appropriate would be another consideration.
Antipsychotics may be used to treat a variety of psychiatric disorders, with the second-generation antipsychotics SGAs used more frequently due to their more favorable side-effect profile compared to the first-generation antipsychotics FGAs.
Aripiprazole may also be a reasonable option in adults, as no reports have found false-positive results in this population.
However, pharmacists should carefully consider the possibility of a positive result being false should one occur with a patient on aripiprazole. Many of the FGAs cause false-positive UDS results and have a less favorable side-effect profile compared to the SGAs; thus, minimizing use of these agents when possible would be suggested.
Antiemetics In addition to the antiemetics promethazine and doxylamine, metoclopramide and prochlorperazine have had documented false-positive LSD results. Ciprofloxacin, moxifloxacin, and norfloxacin showed cross-reactivity to opiates because of similar molecular structures, but at lower levels than most immunoassay thresholds.
Thus, these agents may be less likely to cause false-positives. Antihistamines, analgesics, cough suppressants, and heartburn medications have been shown to cause false-positives in studies and case reports.
Consider using second-generation antihistamines, as they have not been reported to cause false-positive UDS results. Both ibuprofen and naproxen have been documented to cause false-positive barbiturate4 and cannabinoid levels.
In addition, ibuprofen can cause a false-positive PCP level. Lastly, heartburn medications have been documented to interact with UDS tests to cause false-positives.While many of today's medical tests are accurate, false negative or positives do occur. What causes these erroneous results?
A false negative is a test result that indicates a person does not have. The ideal HIV screening assay would correctly identify all HIV-positive and HIV-negative individuals % of the time.
While real-world procedures are extremely accurate, they do . a. Of or relating to being or the possession of qualities rather than non-being or the absence of qualities: the question of the positive existence of evil.
Tthe future of positive thinking research is promising. There is a large, scientifically valid body of research that indicates that optimistic people are generally better off in . The false positive rate is the proportion of all negatives that still yield positive test outcomes, i.e., the conditional probability of a positive test result given an event that was not present..
The false positive rate is equal to the significance ashio-midori.com specificity of the test is equal to 1 minus the false positive rate.. In statistical hypothesis testing, this fraction is given the. How to Be Positive.
In this Article: Article Summary Starting With Yourself Surrounding Yourself With Positive Influences Avoiding Negative Influences Community Q&A When we think of the word “positive,” most of us probably think “happy.” However, happiness isn’t the only type of positivity.