Statistical interactions expressed as RIRRs representing an estimate of the ratio of the individual incidence rate ratios for the defined groups (A–F) for the stated periods as defined in the ‘Methods’ section
| A. All workers: agent has WEL versus do not have WEL | B. All workers: agent has WEL versus do not have WEL (excluding one reporter) | |||||
|---|---|---|---|---|---|---|
| ID | 2004 amendment to 2002 COSHH regulations | Period | Type of ill-health | Periods compared | RIRR (95% CIs) | RIRR (95% CIs) |
| 1a | Introduction of a WEL (25 April 2005) | time 1=January 2003 to April 2005 | SLRD | Time 2/time 1 | 0.70 (0.52 to 0.93) | 0.65 (0.46 to 0.91) |
| time 2=May 2005 to December 2008 | Asthma | Time 2/time 1 | 0.71 (0.50 to 1.02) | 0.66 (0.43 to 1.01) | ||
| 1b | Introduction of a WEL with a 20-month intermediate period (25 April 2005) | time 1=January 2003 to April 2005 time 2=May 2005 to December 2006 time 3=January 2007 to December 2008 | SLRD | Time 2/time 1 | 0.66 (0.47 to 0.92) | 0.63 (0.43 to 0.94) |
| Time 3/time 1 | 0.74 (0.52 to 1.06) | 0.67 (0.44 to 1.00) | ||||
| Asthma | Time 2/time 1 | 0.61 (0.41 to 0.90) | 0.59 (0.37 to 0.96) | |||
| Time 3/time 1 | 0.87 (0.57 to 1.34) | 0.74 (0.44 to 1.25) | ||||
| ID | Events affecting exposure to glutaraldehyde-based disinfectants | Period | Type of ill-health | Periods compared | C. All workers: glutaraldehyde versus other agents | D. Healthcare sector: glutaraldehyde versus other agents |
| RIRR (95% CIs) | RIRR (95% CIs) | |||||
| 2 | Introduction of a MEL (25 March 1999) Withdrawal of Cidex (May 2002) Introduction of a WEL (25 April 2005) | time 1=January 1996 to March 1999 time 2=April 1999 to May 2002 time 3=June 2002 to April 2005 time 4=May 2005 to December 2008 | SLRD | Time 2/time 1 | 0.66 (0.40 to 1.11) | 0.41 (0.21 to 0.78) |
| Time 3/time 1 | 0.44 (0.24 to 0.82) | 0.52 (0.24 to 1.14) | ||||
| Time 4/time 1 | 0.13 (0.05 to 0.36) | 0.07 (0.02 to 0.32) | ||||
| Time 3/time 2 | 0.67 (0.34 to 1.32) | 1.28 (0.56 to 2.91) | ||||
| Time 4/time 2 | 0.20 (0.07 to 0.57) | 0.18 (0.04 to 0.81) | ||||
| Time 4/time 3 | 0.29 (0.10 to 0.89) | NC (-) | ||||
| Asthma | Time 2/time 1 | 0.79 (0.45 to 1.37) | 0.41 (0.20 to 0.82) | |||
| Time 3/time 1 | 0.51 (0.26 to 1.01) | 0.50 (0.26 to 1.18) | ||||
| Time 4/time 1 | 0.17 (0.06 to 0.49) | 0.08 (0.02 to 0.34) | ||||
| Time 3/time 2 | 0.65 (0.32 to 1.34) | 1.23 (0.51 to 2.99) | ||||
| Time 4/time 2 | 0.22 (0.08 to 0.64) | 0.19 (0.04 to 0.85) | ||||
| Time 4/time 3 | 0.34 (0.11 to 1.06) | NC (-) | ||||
| ID | Events affecting exposure to latex | Periods | Type of ill-health | Time periods compared | E. All workers: latex versus other agents | F. Healthcare sector: latex versus other agents |
| RIRR (95% CIs) | RIRR (95% CIs) | |||||
| 3 | MDA mandatory advice (June 1998) HSE guidance (April 2000) 2004 COSHH amendment (April 2005) | time 1=January 1996 to June 1998 time 2=July 1998 to April 2000 time 3=May 2000 to April 2005 time 4=May 2005 to December 2008 | SLRD | Time 2/time 1 | 1.11 (0.62 to 1.99) | 1.14 (0.51 to 2.55) |
| Time 3/time 2 | 0.62 (0.35 to 1.09) | 0.73 (0.35 to 1.53) | ||||
| Time 4/time 2 | 0.23 (0.10 to 0.55) | 0.40 (0.14 to 1.17) | ||||
| Time 4/time 3 | 0.37 (0.16 to 0.85) | 0.55 (0.21 to 1.49) | ||||
| Asthma | Time 2/time 1 | 1.13 (0.62 to 2.06) | NC (-) | |||
| Time 3/time 2 | 0.67 (0.38 to 1.19) | NC (-) | ||||
| Time 4/time 2 | 0.26 (0.11 to 0.62) | NC (-) | ||||
| Time 4/time 3 | 0.39 (0.17 to 0.89) | NC (-) | ||||
The RIRR can be considered as an estimate of the magnitude of the difference in the change in incidence between the groups over the defined time periods.
Cidex, a glutaraldehyde-based disinfectant supplying a large proportion of the UK market; COSHH, Control of Substances Hazardous to Health; HSE, UK Health and Safety Executive; NC, model did not converge; MDA, UK Medical Devices Agency; MEL, maximum exposure limit; RIRR, ratio of incidence rate ratios or interaction term; SLRD, short latency respiratory disease (includes asthma, allergic alveolitis, rhinitis, inhalation accidents); WEL, workplace exposure limit.