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resistance() should be used to calculate resistance, susceptibility() should be used to calculate susceptibility."><title>Calculate Microbial Resistance — proportion • AMR (for R)</title><!-- favicons --><linkrel="icon"type="image/png"sizes="16x16"href="../favicon-16x16.png"><linkrel="icon"type="image/png"sizes="32x32"href="../favicon-32x32.png"><linkrel="apple-touch-icon"type="image/png"sizes="180x180"href="../apple-touch-icon.png"><linkrel="apple-touch-icon"type="image/png"sizes="120x120"href="../apple-touch-icon-120x120.png"><linkrel="apple-touch-icon"type="image/png"sizes="76x76"href="../apple-touch-icon-76x76.png"><linkrel="apple-touch-icon"type="image/png"sizes="60x60"href="../apple-touch-icon-60x60.png"><scriptsrc="../deps/jquery-3.6.0/jquery-3.6.0.min.js"></script><metaname="viewport"content="width=device-width, initial-scale=1, shrink-to-fit=no"><linkhref="../deps/bootstrap-5.1.3/bootstrap.min.css"rel="stylesheet"><scriptsrc="../deps/bootstrap-5.1.3/bootstrap.bundle.min.js"></script><linkhref="../deps/Fira_Code-0.4.2/font.css"rel="stylesheet"><!-- Font Awesome icons --><linkrel="stylesheet"href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.12.1/css/all.min.css"integrity="sha256-mmgLkCYLUQbXn0B1SRqzHar6dCnv9oZFPEC1g1cwlkk="crossorigin="anonymous"><linkrel="stylesheet"href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.12.1/css/v4-shims.min.css"integrity="sha256-wZjR52fzng1pJHwx4aV2AO3yyTOXrcDW7jBpJtTwVxw="crossorigin="anonymous"><!-- bootstrap-toc --><scriptsrc="https://cdn.rawgit.com/afeld/bootstrap-toc/v1.0.1/dist/bootstrap-toc.min.js"></script><!-- headroom.js --><scriptsrc="https://cdnjs.cloudflare.com/ajax/libs/headroom/0.11.0/headroom.min.js"integrity="sha256-AsUX4SJE1+yuDu5+mAVzJbuYNPHj/WroHuZ8Ir/CkE0="crossorigin="anonymous"></script><scriptsrc="https://cdnjs.cloudflare.com/ajax/libs/headroom/0.11.0/jQuery.headroom.min.js"integrity="sha256-ZX/yNShbjqsohH1k95liqY9Gd8uOiE1S4vZc+9KQ1K4="crossorigin="anonymous"></script><!-- clipboard.js --><scriptsrc="https://cdnjs.cloudflare.com/ajax/libs/clipboard.js/2.0.6/clipboard.min.js"integrity="sha256-inc5kl9MA1hkeYUt+EC3BhlIgyp/2jDIyBLS6k3UxPI="crossorigin="anonymous"></script><!-- search --><scriptsrc="https://cdnjs.cloudflare.com/ajax/libs/fuse.js/6.4.6/fuse.js"integrity="sha512-zv6Ywkjyktsohkbp9bb45V6tEMoWhzFzXis+LrMehmJZZSys19Yxf1dopHx7WzIKxr5tK2dVcYmaCk2uqdjF4A=="crossorigin="anonymous"></script><scriptsrc="https://cdnjs.cloudflare.com/ajax/libs/autocomplete.js/0.38.0/autocomplete.jquery.min.js"integrity="sha512-GU9ayf+66Xx2TmpxqJpliWbT5PiGYxpaG8rfnBEk1LL8l1KGkRShhngwdXK1UgqhAzWpZHSiYPc09/NwDQIGyg=="crossorigin="anonymous"></script><scriptsrc="https://cdnjs.cloudflare.com/ajax/libs/mark.js/8.11.1/mark.min.js"integrity="sha512-5CYOlHXGh6QpOFA/TeTylKLWfB3ftPsde7AnmhuitiTX4K5SqCLBeKro6sPS8ilsz1Q4NRx3v8Ko2IBiszzdww=="crossorigin="anonymous"></script><!-- pkgdown --><scriptsrc="../pkgdown.js"></script><linkhref="../extra.css"rel="stylesheet"><scriptsrc="../extra.js"></script><metaproperty="og:title"content="Calculate Microbial Resistance — proportion"><metaproperty="og:description"content="Thesefunctionscanbeusedtocalculatethe(co-)resistanceorsusceptibilityofmicrobialisolates(i.e.percentageofS,SI,I,IRorR).Allfunctionssupportquasiquotationwithpipes,canbeusedinsummarise()fromthedplyrpackageandalsosupportgroupedvariables,seeExamples.
resistance() should be used to calculate resistance, susceptibility() should be used to calculate susceptibility."><metaproperty="og:image"content="https://msberends.github.io/AMR/logo.svg"><metaname="twitter:card"content="summary_large_image"><metaname="twitter:creator"content="@msberends"><metaname="twitter:site"content="@msberends"><!-- mathjax --><scriptsrc="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/MathJax.js"integrity="sha256-nvJJv9wWKEm88qvoQl9ekL2J+k/RWIsaSScxxlsrv8k="crossorigin="anonymous"></script><scriptsrc="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/config/TeX-AMS-MML_HTMLorMML.js"integrity="sha256-84DKXVJXs0/F8OTMzX4UR909+jtl4G7SPypPavF+GfA="crossorigin="anonymous"></script><!--[if lt IE 9]>
<p>These functions can be used to calculate the (co-)resistance or susceptibility of microbial isolates (i.e. percentage of S, SI, I, IR or R). All functions support quasiquotation with pipes, can be used in <code><ahref="https://dplyr.tidyverse.org/reference/summarise.html"class="external-link">summarise()</a></code> from the <code>dplyr</code> package and also support grouped variables, see <em>Examples</em>.</p>
<p><code>resistance()</code> should be used to calculate resistance, <code>susceptibility()</code> should be used to calculate susceptibility.<br></p>
<span> language <spanclass="op">=</span><spanclass="fu"><ahref="translate.html">get_AMR_locale</a></span><spanclass="op">(</span><spanclass="op">)</span>,</span>
<span> language <spanclass="op">=</span><spanclass="fu"><ahref="translate.html">get_AMR_locale</a></span><spanclass="op">(</span><spanclass="op">)</span>,</span>
<p><strong>M39 Analysis and Presentation of Cumulative Antimicrobial Susceptibility Test Data, 5th Edition</strong>, 2022, <em>Clinical and Laboratory Standards Institute (CLSI)</em>. <ahref="https://clsi.org/standards/products/microbiology/documents/m39/"class="external-link">https://clsi.org/standards/products/microbiology/documents/m39/</a>.</p>
<dd><p>one or more vectors (or columns) with antibiotic interpretations. They will be transformed internally with <code><ahref="as.rsi.html">as.rsi()</a></code> if needed. Use multiple columns to calculate (the lack of) co-resistance: the probability where one of two drugs have a resistant or susceptible result. See <em>Examples</em>.</p></dd>
<dt>minimum</dt>
<dd><p>the minimum allowed number of available (tested) isolates. Any isolate count lower than <code>minimum</code> will return <code>NA</code> with a warning. The default number of <code>30</code> isolates is advised by the Clinical and Laboratory Standards Institute (CLSI) as best practice, see <em>Source</em>.</p></dd>
<dt>as_percent</dt>
<dd><p>a <ahref="https://rdrr.io/r/base/logical.html"class="external-link">logical</a> to indicate whether the output must be returned as a hundred fold with % sign (a character). A value of <code>0.123456</code> will then be returned as <code>"12.3%"</code>.</p></dd>
<dt>only_all_tested</dt>
<dd><p>(for combination therapies, i.e. using more than one variable for <code>...</code>): a <ahref="https://rdrr.io/r/base/logical.html"class="external-link">logical</a> to indicate that isolates must be tested for all antibiotics, see section <em>Combination Therapy</em> below</p></dd>
<dd><p>antibiotic results to test against, must be one of more values of "R", "S", "I"</p></dd>
<dt>confidence_level</dt>
<dd><p>the confidence level for the returned confidence interval. For the calculation, the number of S or SI isolates, and R isolates are compared with the total number of available isolates with R, S, or I by using <code><ahref="https://rdrr.io/r/stats/binom.test.html"class="external-link">binom.test()</a></code>, i.e., the Clopper-Pearson method.</p></dd>
<dt>side</dt>
<dd><p>the side of the confidence interval to return. Defaults to <code>"both"</code> for a length 2 vector, but can also be (abbreviated as) <code>"min"</code>/<code>"left"</code>/<code>"lower"</code>/<code>"less"</code> or <code>"max"</code>/<code>"right"</code>/<code>"higher"</code>/<code>"greater"</code>.</p></dd>
<dd><p>a <ahref="https://rdrr.io/r/base/data.frame.html"class="external-link">data.frame</a> containing columns with class <code><ahref="as.rsi.html">rsi</a></code> (see <code><ahref="as.rsi.html">as.rsi()</a></code>)</p></dd>
<dt>translate_ab</dt>
<dd><p>a column name of the <ahref="antibiotics.html">antibiotics</a> data set to translate the antibiotic abbreviations to, using <code><ahref="ab_property.html">ab_property()</a></code></p></dd>
<dt>language</dt>
<dd><p>language of the returned text, defaults to system language (see <code><ahref="translate.html">get_AMR_locale()</a></code>) and can also be set with <code>getOption("AMR_locale")</code>. Use <code>language = NULL</code> or <code>language = ""</code> to prevent translation.</p></dd>
<dd><p>a <ahref="https://rdrr.io/r/base/logical.html"class="external-link">logical</a> to indicate whether all values of S and I must be merged into one, so the output only consists of S+I vs. R (susceptible vs. resistant), defaults to <code>TRUE</code></p></dd>
<p>A <ahref="https://rdrr.io/r/base/double.html"class="external-link">double</a> or, when <code>as_percent = TRUE</code>, a <ahref="https://rdrr.io/r/base/character.html"class="external-link">character</a>.</p>
<p>The function <code>resistance()</code> is equal to the function <code>proportion_R()</code>. The function <code>susceptibility()</code> is equal to the function <code>proportion_SI()</code>.</p>
<p>Use <code>rsi_confidence_interval()</code> to calculate the confidence interval, which relies on <code><ahref="https://rdrr.io/r/stats/binom.test.html"class="external-link">binom.test()</a></code>, i.e., the Clopper-Pearson method. This function returns a vector of length 2 at default for antimicrobial <em>resistance</em>. Change the <code>side</code> argument to "left"/"min" or "right"/"max" to return a single value, and change the <code>ab_result</code> argument to e.g. <code>c("S", "I")</code> to test for antimicrobial <em>susceptibility</em>, see Examples.</p>
<p><strong>Remember that you should filter your data to let it contain only first isolates!</strong> This is needed to exclude duplicates and to reduce selection bias. Use <code><ahref="first_isolate.html">first_isolate()</a></code> to determine them in your data set.</p>
<p>These functions are not meant to count isolates, but to calculate the proportion of resistance/susceptibility. Use the <code><ahref="count.html">count()</a></code> functions to count isolates. The function <code>susceptibility()</code> is essentially equal to <code>count_susceptible() / count_all()</code>. <em>Low counts can influence the outcome - the <code>proportion</code> functions may camouflage this, since they only return the proportion (albeit being dependent on the <code>minimum</code> argument).</em></p>
<p>The function <code>proportion_df()</code> takes any variable from <code>data</code> that has an <code><ahref="as.rsi.html">rsi</a></code> class (created with <code><ahref="as.rsi.html">as.rsi()</a></code>) and calculates the proportions R, I and S. It also supports grouped variables. The function <code>rsi_df()</code> works exactly like <code>proportion_df()</code>, but adds the number of isolates.</p>
<p>When using more than one variable for <code>...</code> (= combination therapy), use <code>only_all_tested</code> to only count isolates that are tested for all antibiotics/variables that you test them for. See this example for two antibiotics, Drug A and Drug B, about how <code>susceptibility()</code> works to calculate the %SI:</p>
<spanid="cb1-7"><ahref="#cb1-7"aria-hidden="true"tabindex="-1"></a> S or I S or I X X X X</span>
<spanid="cb1-8"><ahref="#cb1-8"aria-hidden="true"tabindex="-1"></a> R S or I X X X X</span>
<spanid="cb1-9"><ahref="#cb1-9"aria-hidden="true"tabindex="-1"></a><spanclass="sc"><</span><spanclass="cn">NA</span><spanclass="sc">></span> S or I X X <spanclass="sc">-</span><spanclass="sc">-</span></span>
<spanid="cb1-10"><ahref="#cb1-10"aria-hidden="true"tabindex="-1"></a> S or I R X X X X</span>
<spanid="cb1-11"><ahref="#cb1-11"aria-hidden="true"tabindex="-1"></a> R R <spanclass="sc">-</span> X <spanclass="sc">-</span> X</span>
<spanid="cb1-12"><ahref="#cb1-12"aria-hidden="true"tabindex="-1"></a><spanclass="sc"><</span><spanclass="cn">NA</span><spanclass="sc">></span> R <spanclass="sc">-</span><spanclass="sc">-</span><spanclass="sc">-</span><spanclass="sc">-</span></span>
<spanid="cb1-13"><ahref="#cb1-13"aria-hidden="true"tabindex="-1"></a> S or I <spanclass="sc"><</span><spanclass="cn">NA</span><spanclass="sc">></span> X X <spanclass="sc">-</span><spanclass="sc">-</span></span>
<spanid="cb1-14"><ahref="#cb1-14"aria-hidden="true"tabindex="-1"></a> R <spanclass="sc"><</span><spanclass="cn">NA</span><spanclass="sc">></span><spanclass="sc">-</span><spanclass="sc">-</span><spanclass="sc">-</span><spanclass="sc">-</span></span>
<p>Using <code>only_all_tested</code> has no impact when only using one antibiotic as input.</p>
</div>
<divclass="section level2">
<h2id="interpretation-of-r-and-s-i">Interpretation of R and S/I<aclass="anchor"aria-label="anchor"href="#interpretation-of-r-and-s-i"></a></h2>
<p>In 2019, the European Committee on Antimicrobial Susceptibility Testing (EUCAST) has decided to change the definitions of susceptibility testing categories R and S/I as shown below (<ahref="https://www.eucast.org/newsiandr/"class="external-link">https://www.eucast.org/newsiandr/</a>).</p><ul><li><p><strong>R = Resistant</strong><br>
A microorganism is categorised as <em>Resistant</em> when there is a high likelihood of therapeutic failure even when there is increased exposure. Exposure is a function of how the mode of administration, dose, dosing interval, infusion time, as well as distribution and excretion of the antimicrobial agent will influence the infecting organism at the site of infection.</p></li>
<li><p><strong>S = Susceptible</strong><br>
A microorganism is categorised as <em>Susceptible, standard dosing regimen</em>, when there is a high likelihood of therapeutic success using a standard dosing regimen of the agent.</p></li>
A microorganism is categorised as <em>Susceptible, Increased exposure</em> when there is a high likelihood of therapeutic success because exposure to the agent is increased by adjusting the dosing regimen or by its concentration at the site of infection.</p></li>
</ul><p>This AMR package honours this (new) insight. Use <code>susceptibility()</code> (equal to <code>proportion_SI()</code>) to determine antimicrobial susceptibility and <code><ahref="count.html">count_susceptible()</a></code> (equal to <code><ahref="count.html">count_SI()</a></code>) to count susceptible isolates.</p>
<divclass="sourceCode"><preclass="sourceCode r"><code><spanclass="r-in"><span><spanclass="co"># example_isolates is a data set available in the AMR package.</span></span></span>
<spanclass="r-in"><span><spanclass="co"># run ?example_isolates for more info.</span></span></span>
<spanclass="r-in"><span></span></span>
<spanclass="r-in"><span><spanclass="co"># base R ------------------------------------------------------------</span></span></span>
<spanclass="r-in"><span> r <spanclass="op">=</span><spanclass="fu">resistance</span><spanclass="op">(</span><spanclass="va">CIP</span><spanclass="op">)</span>,</span></span>
<spanclass="r-in"><span> n <spanclass="op">=</span><spanclass="fu"><ahref="count.html">n_rsi</a></span><spanclass="op">(</span><spanclass="va">CIP</span><spanclass="op">)</span></span></span>
<spanclass="r-in"><span><spanclass="op">)</span><spanclass="co"># n_rsi works like n_distinct in dplyr, see ?n_rsi</span></span></span>
<spanclass="r-in"><span> ci_min <spanclass="op">=</span><spanclass="fu">rsi_confidence_interval</span><spanclass="op">(</span><spanclass="va">CIP</span>, side <spanclass="op">=</span><spanclass="st">"min"</span><spanclass="op">)</span>,</span></span>
<spanclass="r-in"><span> ci_max <spanclass="op">=</span><spanclass="fu">rsi_confidence_interval</span><spanclass="op">(</span><spanclass="va">CIP</span>, side <spanclass="op">=</span><spanclass="st">"max"</span><spanclass="op">)</span>,</span></span>
<spanclass="r-in"><span> R <spanclass="op">=</span><spanclass="fu">resistance</span><spanclass="op">(</span><spanclass="va">CIP</span>, as_percent <spanclass="op">=</span><spanclass="cn">TRUE</span><spanclass="op">)</span>,</span></span>
<spanclass="r-in"><span> SI <spanclass="op">=</span><spanclass="fu">susceptibility</span><spanclass="op">(</span><spanclass="va">CIP</span>, as_percent <spanclass="op">=</span><spanclass="cn">TRUE</span><spanclass="op">)</span>,</span></span>
<spanclass="r-in"><span> n1 <spanclass="op">=</span><spanclass="fu"><ahref="count.html">count_all</a></span><spanclass="op">(</span><spanclass="va">CIP</span><spanclass="op">)</span>, <spanclass="co"># the actual total; sum of all three</span></span></span>
<spanclass="r-in"><span> n2 <spanclass="op">=</span><spanclass="fu"><ahref="count.html">n_rsi</a></span><spanclass="op">(</span><spanclass="va">CIP</span><spanclass="op">)</span>, <spanclass="co"># same - analogous to n_distinct</span></span></span>
<spanclass="r-in"><span> total <spanclass="op">=</span><spanclass="fu"><ahref="https://dplyr.tidyverse.org/reference/context.html"class="external-link">n</a></span><spanclass="op">(</span><spanclass="op">)</span></span></span>
<spanclass="r-in"><span><spanclass="op">)</span><spanclass="co"># NOT the number of tested isolates!</span></span></span>
<spanclass="r-in"><span><spanclass="va">example_isolates</span><spanclass="op"><ahref="https://magrittr.tidyverse.org/reference/pipe.html"class="external-link">%>%</a></span><spanclass="fu"><ahref="count.html">count_all</a></span><spanclass="op">(</span><spanclass="va">AMC</span><spanclass="op">)</span><spanclass="co"># n = 1879</span></span></span>
<spanclass="r-in"><span><spanclass="va">example_isolates</span><spanclass="op"><ahref="https://magrittr.tidyverse.org/reference/pipe.html"class="external-link">%>%</a></span><spanclass="fu"><ahref="count.html">count_all</a></span><spanclass="op">(</span><spanclass="va">GEN</span><spanclass="op">)</span><spanclass="co"># n = 1855</span></span></span>
<spanclass="r-in"><span><spanclass="va">example_isolates</span><spanclass="op"><ahref="https://magrittr.tidyverse.org/reference/pipe.html"class="external-link">%>%</a></span><spanclass="fu"><ahref="count.html">count_all</a></span><spanclass="op">(</span><spanclass="va">AMC</span>, <spanclass="va">GEN</span><spanclass="op">)</span><spanclass="co"># n = 1939</span></span></span>
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