Rapid-response teams have little effect on cardiac arrest deaths

Your title is very misleading and not at all what the article claims. This was a study of one hospital, at one point in time, looking at the effect of one intervention pre-and post-study. The article does not claim that "rapid-response teams have little to no effect in reducing cardiac arrest or deaths in hospitals." Other research over a greater amount of time and involving multiple facilities have found that rapid response teams "in hospitals" do have an effect on mortality after codes have been called. For one thing, this study involved small numbers of deaths, making the reporting of percentages misleading. It appears that there was no control for acuity of the patient (would the patient have died anyway?), or the reason the RRT was called into action (some are called by staff and families when there is evidence of deterioration and not only due to codes). Measuring a hospital against itself would qualify as a preliminary study, but you don't know what else you are measuring unless it's explicitly accounted for, such as internal policies and procedures that may inadvertently lead to more or fewer deaths. An organization may make the same mistake in each case without realizing that their processes are contributing to the outcome.
Please remember that "the plural of anecdote is not data." To go from this simple preliminary study to a generalized claim that "RRT's" have "little effect" "in hospitals" is a total over-reading of the claim made in the article about their hospital and could be construed to be another example of journalistic sensationalism based on a lack of understanding of epidemiological studies or methodology.