Introduction
Case 1
Case 2
Case 3
Methods
Data sources and case definition
Mortality rates
Results
Dermatomyositis | Polymyositis | ||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
UCD | MCD | UCD | MCD | ||||||||||||
Year | No | Rate | No | Rate | U/M | No | Rate | No | Rate | U/M | |||||
1981–2020 | 3985 | 0.34 | 8264 | 0.71 | 0.48 | 7097 | 0.61 | 15,344 | 1.32 | 0.46 | |||||
1981–1982 | 208 | 0.49 | 421 | 0.99 | 0.50 | 328 | 0.79 | 755 | 1.83 | 0.43 | |||||
1983–1984 | 208 | 0.40 | 397 | 0.93 | 0.44 | 342 | 0.79 | 796 | 1.85 | 0.43 | |||||
1985–1986 | 208 | 0.38 | 394 | 0.89 | 0.43 | 368 | 0.84 | 876 | 2.00 | 0.42 | |||||
1987–1988 | 177 | 0.38 | 404 | 0.88 | 0.43 | 376 | 0.83 | 912 | 2.00 | 0.41 | |||||
1989–1990 | 174 | 0.37 | 394 | 0.83 | 0.44 | 442 | 0.95 | 946 | 2.02 | 0.47 | |||||
1991–1992 | 168 | 0.34 | 382 | 0.78 | 0.44 | 408 | 0.84 | 990 | 2.03 | 0.41 | |||||
1993–1994 | 186 | 0.37 | 423 | 0.83 | 0.44 | 425 | 0.84 | 944 | 1.86 | 0.45 | |||||
1995–1996 | 182 | 0.35 | 416 | 0.79 | 0.44 | 384 | 0.73 | 918 | 1.74 | 0.42 | |||||
1997–1998 | 188 | 0.34 | 402 | 0.74 | 0.47 | 408 | 0.75 | 875 | 1.61 | 0.47 | |||||
1999–2000 | 213 | 0.38 | 433 | 0.77 | 0.49 | 433 | 0.77 | 909 | 1.63 | 0.48 | |||||
2001–2002 | 199 | 0.35 | 441 | 0.77 | 0.45 | 379 | 0.66 | 778 | 1.35 | 0.49 | |||||
2003–2004 | 227 | 0.38 | 445 | 0.75 | 0.51 | 398 | 0.67 | 776 | 1.30 | 0.51 | |||||
2005–2006 | 213 | 0.35 | 417 | 0.68 | 0.51 | 396 | 0.64 | 766 | 1.25 | 0.52 | |||||
2007–2009 | 206 | 0.32 | 409 | 0.64 | 0.51 | 326 | 0.51 | 648 | 1.02 | 0.50 | |||||
2009–2010 | 203 | 0.31 | 402 | 0.61 | 0.51 | 311 | 0.48 | 636 | 0.97 | 0.49 | |||||
2011–2012 | 214 | 0.31 | 418 | 0.61 | 0.51 | 316 | 0.47 | 647 | 0.95 | 0.49 | |||||
2013–2014 | 209 | 0.30 | 398 | 0.56 | 0.53 | 308 | 0.43 | 597 | 0.83 | 0.52 | |||||
2015–2016 | 198 | 0.27 | 391 | 0.54 | 0.51 | 268 | 0.36 | 550 | 0.75 | 0.49 | |||||
2017–2018 | 190 | 0.26 | 404 | 0.54 | 0.48 | 243 | 0.31 | 473 | 0.61 | 0.52 | |||||
2019–2020 | 214 | 0.28 | 473 | 0.60 | 0.46 | 238 | 0.29 | 552 | 0.68 | 0.43 |
Dermatomyositis | Polymyositis | ||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
UCD | MCD | UCD | MCD | ||||||||||||
Year | No | Rate | No | Rate | U/M | No | Rate | No | Rate | U/M | |||||
1981–2020 | 1262 | 0.24 | 2702 | 0.52 | 0.47 | 2625 | 0.52 | 5790 | 1.15 | 0.45 | |||||
1981–1982 | 68 | 0.38 | 135 | 0.76 | 0.50 | 118 | 0.68 | 305 | 1.76 | 0.39 | |||||
1983–1984 | 54 | 0.30 | 139 | 0.78 | 0.38 | 130 | 0.74 | 314 | 1.77 | 0.42 | |||||
1985–1986 | 54 | 0.28 | 144 | 0.75 | 0.37 | 150 | 0.84 | 362 | 2.00 | 0.42 | |||||
1987–1988 | 54 | 0.27 | 144 | 0.72 | 0.37 | 122 | 0.65 | 320 | 1.70 | 0.38 | |||||
1989–1990 | 62 | 0.30 | 142 | 0.69 | 0.43 | 152 | 0.79 | 356 | 1.87 | 0.42 | |||||
1991–1992 | 47 | 0.22 | 126 | 0.61 | 0.37 | 153 | 0.75 | 382 | 1.89 | 0.40 | |||||
1993–1994 | 57 | 0.26 | 124 | 0.57 | 0.46 | 156 | 0.73 | 356 | 1.66 | 0.44 | |||||
1995–1996 | 64 | 0.29 | 138 | 0.62 | 0.46 | 147 | 0.67 | 330 | 1.51 | 0.44 | |||||
1997–1998 | 57 | 0.25 | 134 | 0.57 | 0.43 | 148 | 0.63 | 336 | 1.47 | 0.43 | |||||
1999–2000 | 62 | 0.26 | 121 | 0.49 | 0.52 | 159 | 0.69 | 336 | 1.43 | 0.48 | |||||
2001–2002 | 69 | 0.27 | 150 | 0.59 | 0.46 | 134 | 0.55 | 284 | 1.16 | 0.47 | |||||
2003–2004 | 65 | 0.25 | 127 | 0.49 | 0.51 | 144 | 0.58 | 267 | 1.07 | 0.54 | |||||
2005–2006 | 61 | 0.22 | 110 | 0.40 | 0.56 | 131 | 0.49 | 255 | 0.97 | 0.51 | |||||
2007–2009 | 69 | 0.24 | 140 | 0.49 | 0.48 | 123 | 0.44 | 226 | 0.81 | 0.54 | |||||
2009–2010 | 67 | 0.22 | 134 | 0.45 | 0.50 | 117 | 0.41 | 242 | 0.84 | 0.48 | |||||
2011–2012 | 82 | 0.26 | 142 | 0.45 | 0.58 | 135 | 0.44 | 263 | 0.87 | 0.51 | |||||
2013–2014 | 60 | 0.18 | 134 | 0.41 | 0.44 | 125 | 0.40 | 239 | 0.76 | 0.53 | |||||
2015–2016 | 57 | 0.16 | 119 | 0.34 | 0.47 | 101 | 0.30 | 217 | 0.65 | 0.47 | |||||
2017–2018 | 68 | 0.20 | 125 | 0.37 | 0.55 | 98 | 0.27 | 190 | 0.53 | 0.51 | |||||
2019–2020 | 85 | 0.24 | 174 | 0.47 | 0.50 | 82 | 0.22 | 210 | 0.57 | 0.39 |
Dermatomyositis | Polymyositis | ||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
UCD | MCD | UCD | MCD | ||||||||||||
Year | No | Rate | No | Rate | U/M | No | Rate | No | Rate | U/M | |||||
1981–2020 | 2654 | 0.42 | 5562 | 0.87 | 0.48 | 4472 | 0.69 | 9554 | 1.46 | 0.47 | |||||
1981–1982 | 140 | 0.59 | 286 | 1.20 | 0.50 | 210 | 0.88 | 450 | 1.91 | 0.46 | |||||
1983–1984 | 122 | 0.50 | 258 | 1.06 | 0.47 | 212 | 0.86 | 482 | 1.97 | 0.44 | |||||
1985–1986 | 117 | 0.46 | 250 | 1.00 | 0.46 | 218 | 0.87 | 514 | 2.04 | 0.43 | |||||
1987–1988 | 123 | 0.47 | 260 | 1.00 | 0.47 | 254 | 0.97 | 592 | 2.26 | 0.43 | |||||
1989–1990 | 112 | 0.43 | 252 | 0.96 | 0.45 | 290 | 1.08 | 590 | 2.19 | 0.50 | |||||
1991–1992 | 121 | 0.43 | 256 | 0.93 | 0.46 | 255 | 0.92 | 608 | 2.17 | 0.42 | |||||
1993–1994 | 129 | 0.46 | 299 | 1.04 | 0.44 | 269 | 0.94 | 588 | 2.02 | 0.46 | |||||
1995–1996 | 118 | 0.40 | 278 | 0.93 | 0.42 | 237 | 0.79 | 588 | 1.95 | 0.41 | |||||
1997–1998 | 131 | 0.44 | 268 | 0.89 | 0.49 | 260 | 0.85 | 539 | 1.74 | 0.49 | |||||
1999–2000 | 151 | 0.48 | 312 | 1.00 | 0.48 | 274 | 0.87 | 573 | 1.80 | 0.48 | |||||
2001–2002 | 130 | 0.41 | 291 | 0.91 | 0.45 | 245 | 0.75 | 494 | 1.51 | 0.50 | |||||
2003–2004 | 162 | 0.50 | 318 | 0.97 | 0.51 | 254 | 0.76 | 509 | 1.52 | 0.50 | |||||
2005–2006 | 152 | 0.45 | 307 | 0.91 | 0.50 | 265 | 0.78 | 511 | 1.49 | 0.52 | |||||
2007–2009 | 137 | 0.40 | 269 | 0.77 | 0.52 | 203 | 0.58 | 422 | 1.19 | 0.48 | |||||
2009–2010 | 136 | 0.38 | 268 | 0.75 | 0.51 | 194 | 0.53 | 394 | 1.08 | 0.50 | |||||
2011–2012 | 132 | 0.36 | 276 | 0.74 | 0.48 | 181 | 0.48 | 384 | 1.01 | 0.47 | |||||
2013–2014 | 149 | 0.40 | 264 | 0.69 | 0.57 | 183 | 0.46 | 358 | 0.90 | 0.51 | |||||
2015–2016 | 141 | 0.37 | 272 | 0.70 | 0.52 | 167 | 0.42 | 333 | 0.83 | 0.50 | |||||
2017–2018 | 122 | 0.31 | 279 | 0.70 | 0.45 | 145 | 0.34 | 283 | 0.66 | 0.52 | |||||
2019–2020 | 129 | 0.31 | 299 | 0.71 | 0.44 | 156 | 0.36 | 342 | 0.77 | 0.46 |
Trend 1 | Trend 2 | Trend 3 | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Year | APC | p value | Year | APC | p value | Year | APC | p value | |||
Dermatomyositis, both sexes | |||||||||||
UCD | 1981–1982 to 1985–1986 | − 6.7% | 0.046 | 1985–1986 to 2003–2004 | − 0.1% | 0.681 | 2003–2004 to 2019–2020 | − 0.1% | < 0.001 | ||
MCD | 1981–1982 to 2003–2004 | − 1.2% | < 0.001 | 2003–2004 to 2015–2016 | − 2.5% | < 0.001 | 2015–2016 to 2019–2020 | 2.8% | 0.256 | ||
Dermatomyositis, males | |||||||||||
UCD | 1981–1982 to 2019–2020 | − 1.2% | < 0.001 | ||||||||
MCD | 1981–1982 to 2019–2020 | − 1.9% | < 0.001 | ||||||||
Dermatomyositis, females | |||||||||||
UCD | 1981–1982 to 1989–1990 | − 3.6% | 0.037 | 1989–1990 to 2003–2004 | 0.7% | 0.448 | 2003–2004 to 2019–2020 | − 2.4% | 0.001 | ||
MCD | 1981–1982 to 2003–2004 | − 0.7% | 0.021 | 2003–2004 to 2013–2014 | − 2.8% | 0.048 | 2013–2014 to 2019–2020 | 0.4% | 0.842 | ||
Polymyositis, both sexes | |||||||||||
UCD | 1981–1982 to 1989–1990 | 1.9% | 0.105 | 1989–1990 to 2005–2006 | − 2.3% | < 0.001 | 2005–2006 to 2019–2020 | − 5.2% | < 0.001 | ||
MCD | 1981–1982 to 1991–1992 | 1.3% | 0.115 | 1991–1992 to 2019–2020 | − 4.1% | < 0.001 | |||||
Polymyositis, males | |||||||||||
UCD | 1981–1982 to 1999–2000 | − 0.7% | 0.262 | 1999–2000 to 2019–2020 | − 4.6% | < 0.001 | |||||
MCD | 1981–1982 to 1991–1992 | 0.3% | 0.779 | 1991–1992 to 2019–2020 | − 4.3% | < 0.001 | |||||
Polymyositis, females | |||||||||||
UCD | 1981–1982 to 1999–2000 | − 0.3% | 0.622 | 1999–2000 to 2019–2020 | − 4.7% | < 0.001 | |||||
MCD | 1981–1982 to 1991–1992 | 1.9% | 0.083 | 1991–1992 to 2019–2020 | − 4.0% | < 0.001 |
Discussion
Main findings
Interpreting the findings in the context of previous studies
Authors, year | (1) Period 1 | (2) Period 2 | (2)/(1) | ||||||
---|---|---|---|---|---|---|---|---|---|
(Location) | Myopathy | No | Rate | No | Rate | RR | (95% CI) | ||
Li et al., 2020a [6] | Dermatomyositis | 70 | 80.1 | 73 | 51.3 | 0.64 | (0.46–0.89) | ||
(BC, Canada) | Polymyositis | 79 | 58.6 | 81 | 35.4 | 0.60 | (0.44–0.82) | ||
D’Silva et al., 2021b [9] | Dermatomyositis | 33 | 71.5 | 33 | 49.1 | 0.69 | (0.42–1.11) | ||
(United Kingdom) | Polymyositis | 23 | 42.1 | 25 | 34.4 | 0.82 | (0.46–1.42) |