Statin use and risk of community acquired pneumonia in older people: population based case-control study

Sir,

We read with the greatest interest the paper by Sascha Dublin et al,
(1) and
were struck by an unfathomable mystery, that of the disappearing
gastroprotectives. Proton pump inhibitors, the most widely used acid-
supressing drugs, are a well-known cause of increased risk of community-
acquired pneumonia (2, 3). The authors found an increased use of acid-
suppressing drugs (ASD) in cases (22%) compared to controls (16%) (table
1,
where incidentally they do not indicate statin use), and an increased use
of
ASD in statin users (23.2%) vs non users (14.8%) in controls.
At this point we are anticipating some very nice confounding, and await
with
impatience the rest of the analyses, and the impact of
ASD in the multivariate models, and lo ! to our greatest surprise there is
not a
trace of ASD in the multivariate analysis (table 4). This is extremely
disappointing. Where have all the ASD gone ? We found no reason to remove
them, and could find no explanation in text. It cannot be because the
association was not significant. There are plenty of other associations in
table
4 that are not significant. It can’t be because it finally wasn’t
interesting : not
finding a relation between PPI and pneumonia would be most interesting,
anyhow, since most authors to date found an association (2-4 5) .
Confirming a known association would be more trivial but still
satisfactory.
Willfully dropping a known risk factor for the outcome of interest from a
multivariate analysis is something that is rarely seen.

We remain baffled. Have these drugs been lost or kidnapped? will they

reappear in a further episode? How does the story really end?

Can the authors shed some light on this enigma?

Most sincerely

Ezgi Gulmez, MD, PhD

Nicholas Moore, MD, PhD, FRCP(Edin)

1. Dublin S, Jackson ML, Nelson JC, Weiss NS, Larson EB, Jackson LA.
Statin
use and risk of community acquired pneumonia in older people: population
based case-control study. BMJ 2009;338:b2137.

2. Gulmez SE, Holm A, Frederiksen H, Jensen TG, Pedersen C, Hallas J. Use
of
proton pump inhibitors and the risk of community-acquired pneumonia: a
population-based case-control study. Arch Intern Med 2007;167(9):950-5.

3. Laheij RJ, Sturkenboom MC, Hassing RJ, Dieleman J, Stricker BH, Jansen
JB.
Risk of community-acquired pneumonia and use of gastric acid-suppressive
drugs. JAMA 2004;292(16):1955-60.

4. Myles PR, Hubbard RB, McKeever TM, Pogson Z, Smith CJ, Gibson JE. Risk
of
community-acquired pneumonia and the use of statins, ace inhibitors and
gastric acid suppressants: a population-based case-control study.
Pharmacoepidemiol Drug Saf 2009;18(4):269-75.

5. Sarkar M, Hennessy S, Yang YX. Proton-pump inhibitor use and the risk
for
community-acquired pneumonia. Ann Intern Med 2008;149(6):391-8.

Competing interests:
Beyond a purely professional
interest in this specific topic,
the authors love a good
whodunit, but this one is
beyond them. Could Poirot or
Holmes solve it ?