Table 2.
Factor Loadings From Forced Eight‐Factor Principal Component Analysis of Controls (n = 1306)
| Principal components | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | |
|---|---|---|---|---|---|---|---|---|---|
| Symptoms | Nervous | Skin‐related | Head‐related | Auditory vestibular | Musculo‐skeletal | Allergy‐related | Sensory | Heart/chest‐related | |
| Eigenvalue | 16.41 | 2.77 | 2.22 | 2.08 | 1.58 | 1.53 | 1.52 | 1.32 | |
| Proportion (%) | 28.79 | 4.85 | 3.89 | 3.64 | 2.76 | 2.68 | 2.67 | 2.31 | |
| Cumulative proportion (%) | 28.79 | 33.64 | 37.53 | 41.17 | 43.93 | 46.61 | 49.28 | 51.59 | |
| q12 | Depression | 0.811 | 0.190 | ‐0.363 | 0.302 | ‐0.245 | 0.241 | 0.263 | 0.371 |
| q13 | Difficulty in concentrating | 0.806 | 0.219 | ‐0.347 | 0.282 | ‐0.169 | 0.242 | 0.408 | 0.352 |
| q14 | Difficulty in focusing attention | 0.767 | 0.230 | −0.332 | 0.275 | −0.188 | 0.234 | 0.426 | 0.354 |
| q24 | Fatigue | 0.752 | 0.195 | −0.432 | 0.262 | −0.461 | 0.296 | 0.241 | 0.277 |
| q55 | Stress | 0.721 | 0.199 | −0.373 | 0.203 | −0.377 | 0.232 | 0.248 | 0.260 |
| q25 | Foggy thinking | 0.702 | 0.184 | −0.503 | 0.375 | −0.323 | 0.244 | 0.292 | 0.338 |
| q21 | Exhaustion | 0.669 | 0.161 | −0.468 | 0.231 | −0.426 | 0.314 | 0.234 | 0.266 |
| q2 | Anxiety | 0.633 | 0.194 | −0.184 | 0.165 | −0.229 | 0.381 | 0.099 | 0.320 |
| q34 | Memory difficulties | 0.472 | 0.120 | −0.206 | 0.197 | −0.440 | 0.214 | 0.448 | 0.300 |
| q54 | Sleep disturbances | 0.439 | 0.212 | −0.334 | 0.298 | −0.344 | 0.117 | 0.348 | 0.313 |
| q49 | Skin irritation | 0.232 | 0.757 | −0.212 | 0.270 | −0.248 | 0.307 | 0.166 | 0.168 |
| q52 | Skin redness | 0.235 | 0.741 | −0.236 | 0.187 | −0.071 | 0.342 | 0.165 | 0.228 |
| q53 | Skin swelling | 0.137 | 0.720 | −0.186 | 0.149 | −0.121 | 0.225 | 0.221 | 0.269 |
| q56 | Tingling sensations | 0.193 | 0.689 | −0.203 | 0.284 | −0.270 | 0.105 | 0.290 | 0.192 |
| q41 | Pain/Soreness of the skin | 0.126 | 0.611 | −0.183 | 0.360 | −0.272 | 0.250 | 0.219 | 0.217 |
| q48 | Skin burning sensations | 0.073 | 0.548 | −0.164 | 0.240 | −0.270 | −0.056 | 0.273 | 0.231 |
| q51 | Skin rash | 0.319 | 0.427 | −0.306 | 0.238 | 0.051 | 0.255 | 0.242 | 0.190 |
| q6 | Blisters on the skin | 0.129 | 0.397 | −0.141 | 0.247 | −0.019 | 0.388 | −0.012 | 0.264 |
| q26 | Headaches | 0.349 | 0.162 | −0.881 | 0.277 | −0.224 | 0.206 | 0.196 | 0.266 |
| q20 | Dull headaches | 0.294 | 0.195 | −0.871 | 0.282 | −0.293 | 0.260 | 0.232 | 0.305 |
| q35 | Migraines | 0.198 | 0.115 | −0.851 | 0.187 | −0.157 | 0.125 | 0.217 | 0.193 |
| q28 | Heaviness in the head | 0.436 | 0.195 | −0.803 | 0.301 | −0.339 | 0.196 | 0.208 | 0.356 |
| q46 | Sharp pain in the head | 0.209 | 0.290 | −0.790 | 0.314 | −0.254 | 0.183 | 0.263 | 0.303 |
| q22 | Eye problems | 0.365 | 0.227 | −0.442 | 0.364 | −0.348 | 0.307 | 0.222 | 0.189 |
| q15 | Digestive problems | 0.351 | 0.217 | −0.406 | 0.374 | −0.087 | 0.277 | 0.394 | 0.327 |
| q43 | Pressure in the ear | 0.198 | 0.272 | −0.323 | 0.716 | −0.251 | 0.122 | 0.308 | 0.305 |
| q39 | Pain in the ear | 0.174 | 0.190 | −0.324 | 0.713 | −0.153 | 0.181 | 0.356 | 0.320 |
| q44 | Ringing in the ear | 0.266 | 0.181 | −.0284 | 0.648 | −0.230 | 0.217 | 0.163 | 0.340 |
| q38 | Nausea | 0.331 | 0.196 | −0.420 | 0.561 | −0.182 | 0.327 | 0.355 | 0.382 |
| q23 | Facial prickling | 0.146 | 0.401 | −0.291 | 0.559 | −0.141 | 0.130 | 0.378 | 0.229 |
| q57 | Warmth in the ear | 0.143 | 0.365 | −0.094 | 0.533 | −0.221 | −0.079 | 0.177 | 0.278 |
| q33 | Loss of appetite | 0.390 | 0.078 | −0.365 | 0.437 | −0.065 | 0.209 | 0.414 | 0.267 |
| q42 | Pain/Warmth in the head | 0.264 | 0.259 | −0.257 | 0.436 | −0.275 | 0.225 | 0.205 | 0.370 |
| q36 | Muscle tension | 0.235 | 0.212 | −0.291 | 0.278 | −0.661 | 0.178 | 0.330 | 0.168 |
| q37 | Muscle weakness | 0.270 | 0.190 | −0.225 | 0.477 | −0.591 | 0.153 | 0.335 | 0.268 |
| q40 | Pain in joints | 0.210 | 0.192 | −0.341 | 0.461 | −0.587 | 0.327 | 0.293 | 0.233 |
| q50 | Numbness | 0.255 | 0.339 | −0.238 | 0.421 | −0.568 | 0.125 | 0.253 | 0.285 |
| q47 | Sickness | 0.401 | 0.330 | −0.359 | 0.332 | −0.558 | 0.236 | 0.268 | 0.373 |
| q4 | Back pain | 0.344 | 0.208 | −0.332 | 0.198 | −0.550 | 0.338 | 0.095 | 0.356 |
| q7 | Blurry vision | 0.351 | 0.090 | −0.311 | 0.229 | −0.460 | 0.295 | 0.211 | 0.358 |
| q29 | High blood pressure | 0.097 | 0.099 | −0.151 | −0.041 | −0.387 | 0.052 | 0.235 | 0.310 |
| q1 | Allergies | 0.226 | 0.265 | −0.173 | 0.155 | −0.056 | 0.707 | 0.105 | 0.075 |
| q45 | Runny or stuffy nose | 0.264 | 0.208 | −0.248 | 0.278 | −0.142 | 0.612 | 0.333 | 0.073 |
| q19 | Dry skin | 0.313 | 0.455 | −0.305 | 0.211 | −0.167 | 0.546 | 0.142 | 0.177 |
| q3 | Asthma | 0.054 | 0.063 | −0.037 | −0.046 | −0.130 | 0.525 | 0.106 | 0.197 |
| q18 | Dry cough | 0.164 | 0.089 | −0.231 | 0.199 | −0.252 | 0.497 | 0.320 | 0.320 |
| q5 | Bad taste in the mouth | 0.305 | 0.208 | −0.287 | 0.208 | −0.346 | 0.418 | 0.388 | 0.397 |
| q31 | Impaired sense of smell | 0.105 | 0.153 | −0.134 | 0.179 | −0.132 | 0.193 | 0.789 | 0.173 |
| q32 | Impaired sense of taste | 0.135 | 0.195 | −0.193 | 0.203 | −0.241 | 0.135 | 0.770 | 0.184 |
| q30 | Hoarse dry throat | 0.333 | 0.177 | −0.244 | 0.314 | −0.339 | 0.394 | 0.462 | 0.309 |
| q16 | Disorientation | 0.223 | 0.127 | −0.080 | 0.013 | −0.086 | −0.024 | 0.450 | 0.431 |
| q9 | Cardiac(Heart) pains | 0.178 | 0.161 | −0.268 | 0.268 | −0.168 | 0.124 | 0.231 | 0.824 |
| q10 | Chest pains | 0.254 | 0.228 | −0.318 | 0.312 | −0.279 | 0.226 | 0.298 | 0.782 |
| q8 | Breathing difficulties | 0.318 | 0.214 | −0.260 | 0.360 | −0.383 | 0.374 | 0.292 | 0.644 |
| q27 | Heart palpitations | 0.232 | 0.225 | −0.358 | 0.367 | −0.448 | 0.225 | 0.240 | 0.620 |
| q17 | Dizziness | 0.353 | 0.151 | −0.450 | 0.451 | −0.180 | 0.273 | 0.086 | 0.490 |
| q11 | Cold sweat | 0.385 | 0.265 | −0.194 | 0.299 | −0.056 | 0.229 | 0.268 | 0.473 |
Fifty‐seven symptoms in control group (n = 1,306) were analyzed by forced eight‐factor principal component analysis with oblimin rotation and Kaiser's normalization as described by Eltiti et al. [2007].