Table 1.
A summary of the current studies on the association between smoking and hair loss and PHG
| Author | Quality rating | Study design | Patients, n | Primary diagnosis | Study subjects characteristics | Smoking frequency | Study findings | PHG grading |
|---|---|---|---|---|---|---|---|---|
| Yeo et al. [53] | III | Controlled, retrospective trial | n = 1,371 (945 M, 426 F), 1,743 dropouts | AGA | Mean age of onset: M 33.6 yr, F 29.8 yr. BASP classification system-M: type M (82.2%) >type C (7.5%) >type L (7.3%) >type U (3.0%). F: type M (52.7%) >type L (36.9%) >type C (10.1%) >type U (0.3%) | Not included | F: no correlation between smoking and hair loss. M: subjects who both drank and smoked had more severe hair loss (p = 0.019) than other groups who did not drink or smoke | Not included |
| Su and Chen [8] | IV | Uncontrolled, retrospective trial | n = 740 M, 184 dropouts | AGA | Mean age: 65 yr (40–91 yr). Norwood and Ludwig classification system. In age-groups 40–49, 50–59, 60–69, and ≥70, the age-specific prevalence's of Norwood type A variants were 5.1, 1.1, 8.1, and 7.4%, respectively, and those of female pattern AGA were 0.0, 2.1, 1.6, and 2.4%, respectively | Smoking status group included “Never,” “quit,” “current smoker of <20 cigarettes per day,” or “current smoker of >20 cigarettes per day” | Smokers had an increased risk of having moderate or severe AGA (Norwood type IV) (OR, 1.61; 95% CI, 1.05–2.46). A positive association was established between moderate or severe AGA and smoking status (OR, 1.77; 95% CI, 1.14–2.76), current cigarette smoking of 20 cigarettes or more per day (OR, 2.34; 95% CI, 1.19–4.59), and smoking intensity (smoking duration × amount per day) (OR, 1.78; 95% CI, 1.03–3.07) | Not included |
| Gatherwright et al. [11] | III | Controlled, retrospective trial | n = 98 F | AGA | 98 F identical twins (49 sets). Mean age 53 yr (18–77 yr) | Not included | Less frontal hair loss in twins who had never smoked (p = 0.021; n = 8). Increased frontal hair thinning associated w/being a current smoker and increased pack-years of smoking (p = 0.013 and p = 0.034; n = 10 and n = 24, respectively). Increased temporal hair loss was observed in current smokers (p = 0.096; n = 10) | Not included |
| Gatherwright et al. [11] | III | Controlled, retrospective trial | n = 92 M | AGA | 92 M identical twins (46 sets). Mean age: 52 yr (23–84 yr) | Not included | Positive correlation between smoking history and frontal hair loss (p < 0.001), but quantity of smoking was not statistically significant. Each twin who started smoking earlier (r = −0.798; p < 0.001; n = 20) and stopped smoking later (r = −0.544; p = 0.097; n = 12) had more frontal hair loss. Twins who smoked had more vertex hair loss than their nonsmoking siblings (p = 0.047, n = 20) | Not included |
| Mosley and Gibbs [3] | II | Controlled, retrospective trial | n = 606 (268 M, 338 F) | PHG + hair loss | All subjects were over >30 yr. 152 M and 152 F w/a h/o or current smoking. Hamilton baldness scale (a 5-point scale: score of 1 indicating no hair loss, and 5 indicating extreme baldness). Baldness regarded as present on category III or greater-Bald smokers: 103 M, 2 F; Bald nonsmokers: 63 M, 2 F. PHG smokers: 37 M, 126 F; PHG nonsmokers: 33 M, 110 F | Not included | The odds ratio for the association of smoking and baldness in men was 1.93 (95% confidence interval 1.13–3.28). No corresponding calculation was carried out for females (n = 4). A significant association between gray hair and smoking for all age-groups, in both sexes, w/an overall odds ratio of 4.40 was found (95% CI 3.24–5.96) | Not included |
| Fortes et al. [12] | IV | Uncontrolled, retrospective trial | n = 351 (237 M, 114 F) | AGA | Mean age: 35 yr. M: 133 subjects w/mild (Hamilton-Norwood classifications I–III) and 104 subject's w/moderate/severe (Hamilton-Norwood classifications IV-VII). F: 104 subjects w/mild (Ludwig type I) and 10 subjects moderate/severe (Ludwig types II and III) | Four categories: “Never,” “quit,” “current smokers (<10 cigarettes daily)” “and current smokers (≥10 cigarettes daily)” | Subjects w/more severe AGA tended to smoke more cigarettes per day (≥10 cigarettes daily) than subjects w/less severe AGA (17.5 vs. 7.6%, p = 0.05). AGA subjects that were heavy smokers (≥10 cigarettes per day) had almost 3 times an increased risk of having a moderate/severe alopecia in comparison w/never smokers (p = 0.05) | Not included |
| Fonda-Pascual et al. [24] | IV | Uncontrolled, retrospective trial | n = 72 F | FFA | Mean age at diagnosis 61 yr (32–85 yr) | Documented as “no tobacco exposure” in nonsmokers, and “positive tobacco exposure” in ex-smokers and active smokers. Smoking histories documented in pack-years | Higher prevalence of severe FFA among nonsmokers (p = 0.001). Tobacco exposure was a protective factor against FFA (p = 0.04) | Not included |
| Acer et al. [33] | IV | Controlled, retrospective trial | n = 1,192 (655 F, 537 M) | PHG | 655 F, 537 M (18–20 yr). 377 of the 1,192 subjects had PHG. Mean age of subjects w/PHG was 18.88 yr. Mean onset age of PHG was 16.90 yr (ranges: 7–20 yr). Of the 337 subjects w/PHG, 259 subjects had <10 Gy hairs (68.7%), 88 had (23.3%) 10–100 Gy hairs, and 30 had (8%) >100 Gy hairs | Defined by either the presence or absence of smoking | No relation between smoking and PHG. Of the 377 subjects w/PHG, 288 did not smoke, and 89 were smokers (p = 0.729) | The number of graying hairs was classified as <10, 10–100, and >100 |
| Gould et al. [34] | III | Controlled, retrospective trial | n = 50, 11 dropouts | PHG | 12 of 50 patients had premature graying. PHG started at an early age, ranging from 20 to 35 yr w/an average of 29 yr | Defined by either the presence or absence of smoking in pack-years | Premature graying was not related to the prevalence of smoking | Not included |
| Sabharwal et al. [28] | II | Controlled, retrospective trial | n = 120 | PHG | Mean age: 48.16 yr (smokers), 33.56 yr (tobacco chewers), 33.33 yr (smokers + chewers), and 34.9 yr (control group) | Group I: smoking tobacco (n = 30). Group II: chewing tobacco (n = 30). Group III: smoking + chewing tobacco (n = 30). Group IV: control group (n = 30) |
Increase in the frequency of individuals w/gray hair was observed in 3 groups (groups I, II, and III) when compared w/the control (group IV) (p < 0.05) | Not included |
| Sharma and Dogra [7] | III | Controlled, retrospective trial | n = 240 | PHG | Mean age at onset of graying 13.80 yr (2–22 yr) | Not included | Smoking was associated w/PHG (p = 0.000) | PHG was defined as >5 Gy hair in the scalp in subjects <25 yr. Subjects graded into 4 groups: (1) no gray hair, (2) mild: <10 Gy hair, (3) moderate: 10–100 Gy hair, and (4) severe: >100 Gy hair |
| Shin et al. [32] | III | Controlled, retrospective trial | Pilot n = 1,069 M, 35 dropouts main survey n = 6,390 M, 268 dropouts | PHG | Main survey: of the 6,390 participants, 1,618 (25.3%) presented w/PHG. Subjects had to be <30 yr | Participants w/a smoking history of >5 pack-years were regarded as smokers | Pilot study results: smoking was not associated w/PHG. Main survey: smoking was associated w/PHG (p = 0.014) | Number of gray hairs was self-reported as follows: 0, <10, 10–100, and >100 |
| Jo et al. [29] | III | Controlled, retrospective trial | n = 1,002 | PHG | 522 M and 480 F (12–91 yr). Average overall age at onset of hair graying was 41.6±13.1 yr (M: 40.8±14.1 yr) (W: 42.4±11.9 yr). The prevalence of gray hair by age was 51.5% in their thirties, 81.1% in their forties, and 95.3% in their fifties | Subjects w/a smoking history of >3 pack-years were considered smokers | Age and smoking behavior were correlated w/hair graying. The risk of hair graying increased by 14.9% each year (p < 0.001), and the risk in smokers was 1.99 times higher than that in nonsmokers (p = 0.008) | Subjects estimated the extent of grayness themselves. Grade 1 (<20% of total hair), grade 2 (20–40%), grade 3 (40–60%), grade 4 (60–80%), and grade 5 (>80%). Trained investigators assessed extent of grayness w/a photographic scale (grade 1–5) |
| Aggarwal et al.[31] | III | Controlled, retrospective trial | n = 236 M | PHG | Young subjects (<45 yr) | Group 1: chronic smokers ≤45 yr (n = 62); group 2: subjects w/CAD ≤45 yr and chronic smokers (n = 60); group 3: subjects w/no smoking or cardiac history ≤45 yr (n = 114) | Group II (i.e., smokers w/CAD) had maximum prevalence of graying compared to control (p = 0.000) as well as smoker (group II vs. I p = 0.000) groups. Smokers also had a higher proportion of graying than the control group (group I vs. III p = 0.031) | A 25% or more graying of hair on scalp and/or beard on visual inspection was taken as a positive criterion for graying in the patient |
| Belli et al. [6] | IV | Controlled, retrospective trial | n = 1,119 (372 M, 747 F) | PHG + hair loss | Of 1,119 subjects, 315 (207 F, 108 M; age ranges 14–20 yr, mean age 17.8 yr) had PHG and 804 (540 F, 264 M; age range 14–20 yr, mean age 17.2 yr) did not. The mean onset age of hair graying was 15.6 yr (ranges 5–20 yr) | A smoking history of >1 pack-year was recommended as the cutoff for smoking | Of the 315 participants w/PHG, 254 had fewer than 10 Gy hairs, 54 had 10-100 Gy hairs, and 7 had >100 Gy hairs. Hair loss was higher in participants w/PHG (p = 0.01). Smoking was not associated w/PHG (p = 0.13) | Number of gray hairs was classified as 0, <10, 10–100, >100. Subjects ≥ 1 Gy hairs are considered to have PHG. |
| Zayed et al. [30] | IV | Controlled, retrospective trial | n = 207 (94 M, 113 F) | PHG | Average age of 44 yr. Average age PHG onset 31.7 yr. Of the 207 subjects, 104 had first appearance of gray hair before the age of 30 (PHG group), while the other 103 were considered normal hair graying group | A nonsmoker was defined as someone who never smoked | The prevalence of smokers in the “PHG” group was higher (40.2 vs. 24.7%, p = 0.031). Smokers had earlier onset of hair graying (smokers: 31 [7.4] versus nonsmokers: 34 [8.6], p = 0.034). Smokers were 2 and half times more prone to develop PHG (95% CI: 1.5–4.6) | PHG was defined as the first appearance of gray hair before the age of 30 |
| Matilainen et al. [17] | III | Controlled, retrospective trial | n = 324 F | AGA | Hair status of women was assessed by a modification of Ludwig's scale. The prevalence of extensive hair loss (at least grade II or III on Ludwig's scale) was high (31.2%) | Not included | The prevalence of current smoking was low and equal (13.6%) in both groups, normal hair and extensive hair loss (p = 0.918) | Not included |
| Park et al. [9] | II | Controlled, retrospective trial | n = 1,884 (915 M, 969 F) | AGA | Average age of 56.6 yr. 991 was AGA patients (613 M, 378 F. Of the 991 AGA patients, 443 subjects were classified as having mild AGA, 381 had moderate AGA, and 167 had severe AGA. BASP classification was used to evaluate hair loss | Defined by either the presence or absence of smoking | The prevalence of smokers in the AGA group 334/991 (33.7%) was higher than the non-AGA group 214/893 (24.0%) (p = 0.0000). More severe forms of AGA had a higher frequency of smokers (mild: 125/443 [28.2%], moderate: 143/381 [37.5%], severe: 66/167 [39.5%]) (p = 0.004) | Not included |
| Severi et al. [18] | II | Controlled, retrospective trial | n = 1.390 M | AGA | Interviewers scored AGA according to a set of 4 pictures adapted from the Hamilton-Norwood scale. No balding n = 350 (Hamilton-Norwood stage I), frontal balding n = 447 (Hamilton-Norwood stages II, III, IIIa, and IVa), vertex balding n = 238 (Hamilton-Norwood stage III-vertex and V) and frontal AGA concurrent w/vertex AGA n = 335 (Hamilton-Norwood stages IV, V, Va, VI, and VII) | Defined as either nonsmokers, current smokers, or ex-smokers | The prevalence of frontal only AGA was higher in nonsmokers (199/447) than in current (73/447) and ex-smoker groups (175/447). Vertex only AGA was higher in nonsmokers (106/238) than in current (41/238) and ex-smokers (91/238). Frontal AGA concurrent w/vertex AGA was higher in nonsmokers (173/335) than current (47/335) and ex-smokers (135/335) (p > 0.05) | Not included |
| Salman et al. [19] | IV | Controlled, retrospective trial | n = 954 (419 M, 535 F) | AGA | Average age of 37.7 yr. Average age of AGA onset was 31.1 yr in men and 40.3 in women. AGA prevalence found was 67.1% (n = 281) in men and 23.9% (n = 128) in women. Severity of AGA was evaluated with Norwood-Hamilton scale in men and Ludwig classification in women | Not included | No significant difference was found in terms of smoking habits between patients with and without AGA in both genders (p > 0.05) | Not included |
| Fortes et al. [20] | III | Controlled, prospective trial | n = 214 M | AGA | 104 subjects with AGA and 108 subjects without AGA were included. Average age of subjects with AGA was 28.5 yr and 38.9 in subjects without AGA. Hair pattern was classified according to the Hamilton baldness scale, as modified by Norwood | Cigarette smoking was categorized in 4 groups never, quit, and current smokers (<10 cigarettes; ≥10 cigarettes daily) | No statistical difference was found regarding smoking frequency between AGA subjects when compared to non-AGA subjects (p = 0.13) | Not included |
| Danesh-Shakiba et al. [21] | III | Controlled, prospective trial | n = 512 M | AGA | 256 patients with AGA and 256 age-matched control subjects were included with a mean age of 38.3 and 38.4 yr, respectively. The Norwood-Hamilton scale was employed to determine the presence and severity of AGA in all study participants by one single physician | Current smokers and those who had smoked cigarettes or hookah in the past 30 days were considered cigarette smokers or hookah smokers, respectively | Smoking prevalence was not statistically significant among AGA subjects 72 (28.1%) compared to control subjects 66 (25.8%) (p = 0.550). The prevalence of hookah smoking (smoking water pipe) was not statistically significant among AGA subjects 36 (14%) compared to control subjects 38 (14.8%) (p = 0.801). Although smoking was not significantly more common in patients with mild to moderate hair loss compared to those with severe hair loss (p = 0.276), hookah use was significantly more prevalent in the former group (p < 0.001) | Not included |
| MacDonald et al. [25] | IV | Uncontrolled, retrospective trial | n = 60 W | FFA | Mean age at onset was 60.4 yr and average disease duration was 3.4 years (ranges: 6 months–30 years) | Not included | Data regarding smoking status in FFA patients were available for 52 patients; 37 patients (71%) had never smoked, 5 patients (10%) were current smokers, and 10 patients (19%) were ex-smokers. These data show a significant preponderance of nonsmokers within this cohort, compared with national data regarding smoking status of Scottish women (p = 0.01) | Not included |
| Vora et al. [13] | IV | Controlled, prospective trial | n = 100 M | AGA | 50 subjects with AGA and 50 age-matched control subjects were included with a mean age of 29.32 and 31.5 yr, respectively. The mean age of onset of AGA was 27.08 yr. The degree of androgenic alopecia was based on the Norwood scale (III-VII). AGA developing before 36 yr of age and reaching at least Stage III of Hamilton-Norwood classification is termed as early onset AGA | Not included | The prevalence smoking was higher in male patients with early onset AGA 26 (52%) as compared to controls 11 (22%) (p = 0.002) | Not included |
| Lai et al. [22] | III | Controlled, prospective trial | n = 354 M | AGA | Subjects were men from 35 to 65 yr. The Norwood-Hamilton scale was employed to determine the presence and severity of AGA | Not included | Smoking frequency in subjects with a Hamilton-Norwood scale score of I-III was 175 (59.5%) in smokers and 119 (40.5%) in nonsmokers, while those with a Hamilton-Norwood scale of IV–VII, has a smoking frequency of 35 (58.3%) in smokers and 25 (41.7%) in nonsmokers (p = 0.86) | Not included |
| Huang et al. [14] | III | Controlled, retrospective trial | n = 5,508 (2,142 M, 3,366 F) | AA | 1,377 (517 M, 860 F) subjects with AA and 4,131 (1,625 M, 2,504 F) controls were included with a mean age of 45.0 and 44.4 yr, respectively | Smoking status was considered positive if the patient was a current or past smoker | A higher frequency of current or past smokers (56.5%) with AA was seen compared to subjects with AA who have never smoked (42.6%) | Not included |
| Arias-Santiago et al. [23] | III | Controlled, retrospective trial | n = 154 | AGA | 77 (40 M, 37 F) subjects with early onset AGA and 77 (40 M, 37 F) controls were included. The degree of AGA was determined by the Ebling scale (III–V) for male patients and the Ludwig scale (II–III) for female patients | Smoking status was considered positive if subject smoked >5 cigarettes per day) | Tobacco use was higher in male subjects with AGA (27.5%) versus control subjects (22.5%) p value 0.48. The opposite was true among female smokers with AGA (13.5%) versus control subjects (29.7%) (p = 0.09) | Not included |
| Vañó-Galván et al. [26] | IV | Uncontrolled, retrospective trial | n = 355 (12 M, 343 F) | FFA | The mean age of onset of FFA was 56 yr (21–81 yr). The clinical severity of FFA was classified based on a clinical scale, measuring the area of cicatricial skin produced by the recession of the frontal and temporal hairline. This classification included 5 grades of severity: I (<1 cm), II (1–2.99 cm), III (3–4.99 cm), IV (5–6.99 cm), and V (>7 cm), which were grouped as mild FFA (grades I and II) and severe FFA (grades III, IV, and V) | Smoking was categorized as active smokers, former smokers and those who have never smoked | Smoking habit was recorded in 274 patients or which 237 had never smoked (87%), 26 were former smokers (9%), and 11 (4%) were active smokers | Not included |
| Imhof et al. [27] | IV | Uncontrolled, retrospective trial | n = 148 F | FFA | The mean age of FFA diagnosis was 62.1 yr (28–86 yr). The mean age of FFA symptom onset was 57.4 yr (range, 26-81 yr). Distribution of hair loss was frontal in 147 (99.3%), temporal in 77 (52%), and occipital in 45 (30.4%) | Smoking was categorized as active smokers, former smokers, and those who have never smoked | Smoking history was available for 146 (98.7%) of FFA subjects, with 92 (63%) having never smoked, 54 (37%) were former smokers, and none were active smokers | Not included |
| Thompson et al. [35] | IV | Controlled, prospective trial | n = 467 (113 M, 354 F) | PHG | 216 subjects with a history of PHG and 251 without were included | Smoking history was categorized as never smoker, former smoker, and current smoker | Smoking history (p = 0.015) was significantly negatively correlated with history of PHG. When examining the response from Caucasian participants only, history of PHG remained significantly negatively associated with smoking history (p = 0.008) | PHG was defined as the first appearance of gray hair before the age of 30. Severity of graying was classified as 0, <10, 10–100, >100 gray hairs |
| Maldonado Cid et al. [15] | IV | Uncontrolled, retrospective trial | n = 75 (2 M, 73 F) | FFA | Diagnosis was based on the presence of scarring alopecia with recession of the frontotemporal hairline bilateral diffuse alopecia of the eyebrows, and compatible trichoscopic signs. Of the 75 subjects, mild hairline recession was observed in 56.0% (n = 42) subjects at the first consultation. The mean extent of hairline recession was 2.2±1.5 cm. A diffuse hairline recession pattern was observed in 56.9% (n = 37) of subjects | Smoking history was categorized as nonsmokers, ex-smokers and smokers | While most of the subjects were nonsmokers. Univariate analysis revealed a significant association between smoking and mild hairline recession (p = 0.128) | Not included |
AA, alopecia areata; AGA, androgenic alopecia; BASP, basic and specific; F, female; h/0, history of; L, linear; M, male; n, number of patients; PHG, premature hair graying; RMF, risk multiplication factor; w/, with; w/o, without; FFA, frontal fibrosing alopecia.