Table 2

Age-adjusted incidence rate ratio (IRR) of pneumonia (multiple events) in exposure periods after antidepressant prescription relative to unexposed periods in patients with COPD, calculated by case series analytical technique, UK, 2004–2015

AntidepressantsNo of exposed cases with pneumoniaDays 1–30
IRR (95% CI)		Days 31–60
IRR (95% CI)		Days 61–90
IRR (95% CI)		Days 1–90
IRR (95% CI)		Remainder period
IRR (95% CI)		90 days wash-out
IRR (95% CI)
Collective antidepressants19691.68
(1.33 to 2.13)		1.83
(1.48 to 2.27)		1.89
(1.43 to 2.49)		1.79
(1.54 to 2.07)		1.88
(1.68 to 2.11)		1.03
(0.76 to 1.40)
SSRI or SNRI12181.75
(1.29 to 2.38)		1.62
(1.22 to 2.15)		2.56
(1.88 to 3.50)		1.76
(1.46 to 2.12)		1.83
(1.58 to 2.12)		1.02
(0.69 to 1.50)
SSRI11431.73
(1.62 to 2.39)		1.53
(1.13 to 2.07)		2.65
(1.94 to 3.62)		1.86
(1.54 to 2.4)		1.79
(1.54 to 2.09)		0.95
(0.64 to 1.42)
SNRI1681.69
(0.73 to 3.91)		1.23
(0.53 to 2.86)		1.61
(0.59 to 4.36)		1.48
(0.86 to 2.55)		1.91
(1.31 to 2.79)		1.29
(0.52 to 3.2)
TCA13181.51
(1.10 to 2.03)		1.92
(1.46 to 2.52)		1.40
(0.95 to 2.07)		1.64
(1.35 to 1.98)		1.78
(1.54 to 2.07)		1.29
(0.93 to 1.79)
MAOI500.82
(0.07 to 7.43)		0.93
(0.10 to 8.14)		─0.62
(0.13 to 2.90)		2.44
(0.95 to 5.7)		1.38
(0.33 to 5.77)

  • The ‘collective antidepressants’ does not equate to the total of all individual classes as some subjects received more than one antidepressant in each class.

  • Exposure time periods.

  • 1. Days 1–30: A 30-day risk period starting from the day after the date of the prescription (segment 1).

  • 2. Days 31–60: A 30-day risk period starting from day 31 after the date of the prescription (segment 2).

  • 3. Days 61–90: A 30-day risk period starting from day 61 after the date of prescription (segment 3).

  • 4. Days 1–90: A 90-day risk period accounts for the entire risk window (days 1–90).

  • 5. Remainder period: A period starts 90 days after the date of the prescription until the end of the course (from day 91 after the date of the prescription until the end of the course).

  • 6. 90 days wash-out: A 90-day period starting the day after the end of the course and continuing for 90 days (day one after the end of the course until day 90 after the end of the course).

  • COPD, chronic obstructive pulmonary disease; MAOI, monoamine oxidase inhibitors; SNRI, serotonin-norepinephrine reuptake Inhibitor; SSRI, selective serotonin reuptake inhibitor; TCA, tricyclic antidepressants.