Q: I can’t find anywhere in the AMA Manual of Style guidance on having back-to-back sets of parentheses in running text. Here is an example:
The mean duration of surgery for the computerized-navigation group was 52.6 minutes longer than that of the control group, resulting in a statistically significant difference (P < .05) (Table 1).
I would prefer to see something like this:
The mean duration of surgery for the computerized-navigation group was 52.6 minutes longer than that of the control group, resulting in a statistically significant difference (P < .05; Table 1).
But does the manual have a preference?
A: Short answer: The style manual does not include anything about a pref on use of back-to-back parens, so this is something to think about including in the Punctuation chapter for the 11th edition. (Also, as you’ll see from the few examples below, because we don’t have a policy on this, it has not been handled consistently in our publications.)
Longer answer: Although our first response to your specific example was that we liked the avoidance of back-to-back parens and would favor (as you do) the inclusion of both items in a single set of parens, or would find either version OK, on further thought we decided that this answer was too easy and that often both sets of parens should be retained. Reasons: (1) Although in the example provided it makes sense to combine and use the semicolon, in more complicated sentences it might not be the best choice. (2) Table and Figure citations might be easier to find if not combined with other info.
Below are a few examples from The JAMA Network Journals that might illustrate where combining the information in parens might not be as desirable as keeping the parenthetical items separate.
A significantly higher incidence of SSHL was noted in the HIV group compared with the control group, with an incidence rate ratio (IRR) of 2.17 (95% CI, 1.07-4.40), particularly for the male participants, who had an IRR of 2.23 (1.06-4.69) (Table 2).
Here, keeping the table citation separate makes it clear that the table citation relates to BOTH values given in the sentence, not just the second one. Note that in our journals the first citation of a table or figure is set in different type (here, heavy boldface) to make it stand out.
In this example, where info was combined, it would probably have been better to also have kept the table citation separate as it applied to both bits of info in the sentence:
Mean mandible defect lengths were similar for patients undergoing FFF and LSBF reconstruction (7.8 and 7.7 cm, respectively); STFFs were used to reconstruct significantly shorter defects (mean, 6.0 cm, P<.001, Table 1).
And in this example, which does not include a table or figure citation, similar logic would also probably have made retention of back-to-back parens a better choice since the hazard ratio and P value apply to both, not just the second “n”:
Significantly more patients (n=174) withdrew from the placebo group compared with the chelation group (n=115; hazard ratio, 0.66; P=.001).
Splitting or lumping parentheses should depend more on content than strictly on style.—Cheryl Iverson, MA